About the So-Called ‘UFO Rings’ and Fungi

By Ángel M. Nieves-Rivera

Unidentified Flying Object (UFO) phenomenon has existed since mankind itself. Strange and unexplainable objects have been seen in the skies for millennia.  However, mankind has been making sense of the skies since prehistoric times.  A ‘cascade’ of UFO cases has been described over the years (Hynek 1972; Steiger 1976; Hendry 1979; Klass 1986; Robiou-Lamarche 1979). Nowadays, with the advances of science in astronomy, meteorology, biology, among other fields of applied sciences, the “flying saucer’s myth” is seen today with disdain by scientists for a simple reason: there is no physical evidence for it. UFO cases are based almost entirely on nothing more than personal observation. Although personal testimony is considered to be valid in any court-of-law; however, applied sciences have a more rigorous standard to validate evidence.

For instance, take the “mysterious hovering lights” seen since 1950 to present in NWR Laguna Cartagena, a lagoon located southwestern Puerto Rico. Nowadays scientists know that the lights may have a geophysical origin, triggered by tectonic strains of a fault combined with other geochemical/ physical variables, inducing a phenomenon identical to the “earth lights” recorded worldwide by Strand (1984) and Persinger & Derr (1989). Another example in Puerto Rico is the barren circular patches in cattle’s pastures. After careful examination of various rings, I noted a posthole-shaped depression at the center of the circle, and a lot of hoved animal tracks. By using common sense, one can infer what really happened: a horse was tied up with a rope to the stake, and from that central point the animal ate all the grass around, creating a nearly perfect circle. Then you move the horse to another location and “voilà” . . . a UFO landing ring was created in a matter of hours! Sometimes, people see what they want to see. The purpose of this article is to provide a “down to earth” explanation to the phenomenon known as “UFO landing rings” or “UFO rings.”

UFO Rings.– When a UFO allegedly interacts with the environment and leaves physical or tangible evidence this is called a “Close Encounter of the Second Kind” (or CE-2). This term was coined by the late Dr. J. Allen Hynek, an astronomer who consulted with the US Air Force on Project Blue Book and a lecturer on UFOs for more than 20 years.  According to Hynek (1972) this interaction (what he called “physical trace evidence”) can be with abiotic matter (i.e., marks, holes or rings made on the ground), or with biotic matter, as when plants (i.e., scorching or blighting), animals and humans are affected (i.e., burns, nausea, temporary paralysis). A catalogue of more than a thousand cases in which the UFO was both seen and left physical traces have been compiled by private investigators (Hynek 1972; Steiger 1976; Hendry 1979; Fuller 1997; Phillips 1999).

UFO rings fits the general description provided by Hynek (1972) as “either as circular patch (or patches), uniformly

depressed, burned, or dehydrated, with an overall diameter of 9.1 m or more and 0.3 to 0.9 m thick (the inner and outer diameters of the ring differ by that amount, while the ring itself may be quite large).” The most frequently reported diameters are six to 9.1 m (Hynek 1972). In most cases, the rings persist for weeks or

months– sometimes years– and the interior of the ring or the whole circle remains barren for three to six months

(Hynek 1972; Howe 1999). Scientific explanations to the origin and implications of the UFO rings were reported by Condon (1968). He concludes, however, that the main problem with the UFO rings (CE-2) is the difficulty to  establish as factual the claims that the rings or imprints actually were made by an extraordinary object or being. The existence of an imprint of odd shape, circular area of crushed vegetation or a barren spot often can be established. Its mere existence does not prove, however, that the markings were made by a strange being or vehicle (Condon 1968).

Fungal Diseases.– The alleged UFO rings I had personally seen can be explained away as hoaxes, meteorological effects, or damages to plants caused by natural factors (abiotic and biotic). Abiotic factors, such as chemical and physical soil effects on plant growth are extremely complicated, so that is difficult to describe the effect of one isolated factor and ignore the influence of others. Examples of abiotic factors include mineral nutrition imbalances (Evans et al. 1991), soil alkalinity or acidity, extreme temperatures, soil humidity imbalance, pollution, and over fertilization (Alexander 1991). The examples of biotic factors are diseases, like those caused by insects, nematodes, bacteria, fungi, and viruses (Agrios 1997).

Take turfgrasses for example. Many rings or patches in turfgrasses are caused naturally by fungal (and/or other microorganisms) diseases, which are strikingly similar to “unexplainable” UFO rings or crop rings. Fungi, which naturally occur in topsoil, may become a plant disease under certain favorable conditions—favorable to the fungus— such as stress, wounds, immunodeficiency, etc. (Alexander 1991; Agrios 1997). Fungal diseases such as: Anthracnose and Basal rot (Colletotrichum); Snow mold (Coprinus, Typhula); Red thread (Corticium, Laetisaria); Leaf spots, Blight, Foot rots and Melting-out (Curvularia, Drechslera); Blister smut (Entyloma); Powdery mildew (Erysiphe); Damping-off (Fusarium, Helminthosporium, Pythium, Rhizoctonia); Take-all or Ophiobolus patch (Gaeumannomyces); Root and stem rots (Leptosphaeria, Ophiosphaerella, Sclerotium); Rust (Puccinia); Brown patch (Rhizoctonia); Dollar spot and Snow scald (Sclerotinia); and Stripe smut (Ustilago) commonly infects creeping bentgrass, Kentucky bluegrass or Bermudagrass, among other turfgrasses (Couch 1995; Agrios 1997; Provey & Robinson, 2001; Nieves-Rivera 2001). The photos of diseased turfgrasses presented by Couch (1995), Evans (2000), Provey & Robinson (2001), and those of eyewitnesses of UFO rings (Fuller 1997; Howe 1999) are practically identical. Many of these fungal diseases form rings, spots, or circular formations similar to UFO rings. Curiously, the Powdery mildew caused by the fungus Erysiphe and the Damping-off of seedlings by Pythium produces a white powder or filaments which covers the entire blade of the grass, which remind me of the ‘Angel’s hairs’. These hairs are cobwebs or filaments which sublimate in a few seconds have fallen from the sky and are associated with UFOs.

 Fairy Rings.– Also, fairy rings have been confused with UFO rings. Fairy rings are fungus rings, generally produced by mushrooms (some 60 recorded species), and very frequently occur in grass, grasslands, and woods (Hawksworth et al. 1995). It is a fungus mycelial growth in which the fungus originating in a central spot spreads outward in an ever-widening ring. Fairy rings are not created by gnomes, goblins, or astral entities as suggested by Fernández (2001).

 According to Hawksworth et al. (1995) there are three types of fairy rings: (1) those in which the development of the fruitbodies has no effect on the vegetation, i.e., Chlorophyllum molybdites (see photos in Fernández 2001); (2) those in which there is increased growth of the vegetation, i.e., Calvatia cyathiformis, the fruitbodies of which are at the outer edge of the ring, Lycoperdon gemmatum; and (3) those in which the vegetation is damaged, sometimes so badly as to have an effect on its value, i.e., Agaricus praerimosus and Marasmius oreades.  Rings of the third type are frequently made up of outer and inner rings in which the growth of the vegetation is strong with a ring of dead or badly damaged vegetation between (Hawksworth et al.  1995).

Bioluminescent Fungi.– Among CE-2 cases I have had the opportunity to see and/or read about, include tales about glowing marks on the ground, “phosphorescent patches,” or “ghostly lights” in the forests. Fungi are capable of light up the woods. Bioluminescent mycelium, spores, and fruitbodies of some mushroom species (i.e., Armillaria, Mycena, Omphalotus, Panellus) which usually growth in wood, soil, and leaf litter. The mushrooms produce a non-pulsing light, which attract insects which spread fungal spores. Studies of bioluminescent mushrooms are included in Newton (1952), Herring (1978), O’Kane et al.  (1990), and for excellent photos see <www.luxgene.com>. Bioluminescent fungi are by no means a recent discovery, one of the earliest accounts of  bioluminescent fungi in the New World was published by Spanish chronicler Gonzalo Fernández de Oviedo in 1526 (Glawe & Solberg 1989). Fernández de Oviedo reported how Spanish soldiers “attached bits of luminous rotten wood to their helmets” in order to stay together while making nighttime raids (Glawe & Solberg 1989). I personally have the opportunity to see this curious phenomenon in the Big Tree trail at the Caribbean National Forest El Yunque in Puerto Rico. This might be an explanation to the ghostly green-bluish lights, the glow-in-the-dark (“foxfire” in US), or apparitions seen at night in the forests by the locals since immemorial times and precursors of many folk tales and legends (Nieves-Rivera in press).  Could bioluminescent mycelium be responsible for the glowing effects in the UFO case of the 1970’s– the Delphos sighting? For further details of this case please refer to Klass (1986) and Howe (1999).

Slime Molds.– In 1973, in a small suburb of Dallas (Texas), was terrorized by a moving bright yellow blob of an undetermined organism crawling into house lawns turfgrasses. This yellow blob known as plasmodium was immediately mistaken as an alien entity in the form of microbes that had started an invasion of Earth (Sharnoff 1991; Nieves-Rivera in press). The news kept Curiously, the same F. septica and slime mold Enteridium lycoperdon are named “caca de luna” or ‘Moon’s excrement’ by the locals in the state of Veracruz in Mexico (Nieves-Rivera in press). Slime molds, in general, are decomposers that cover low-lying plants with plasmodium and fructification without “infecting” them, for example, Diachea thomasii and Physarum cinerea. For those who encounter slime molds in turfgrasses and other plants in your yard, “my recommendation would be to avoid using fungicides, mow the lawn, and put your fears to rest!” (Nieves-Rivera 2000).

In conclusion, true fungi (plant pathogenic microfungi, mushrooms) and fungal-like organisms (slime molds) offer an interesting and not too obvious explanation to some of the UFO landing ring cases (catalogued as CE-2), especially for the untrained eye. Future eyewitness accounts of CE-2 should be taken seriously, but every effort should be made to obtain tangible evidence. Not all CE-2 cases are easily explained, but from what I had seen, there is nothing “unearthly” about them. Current evidence suggests that most UFO landing rings are cases of mistaken identity or willful deception.


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Ángel M. Nieves Rivera estudiante doctoral del Departamento de Ciencias Marinas de la Universidad de Puerto Rico en el campus de Mayagüez (UPRM). Trabajó como biólogo residente del Departamento de Recursos Naturales y Ambientales de Puerto Rico. Además Trabajó en un estudio de investigación micológica (estudio de hongos) con el Servicio Forestal del Departamento de Agricultura Federal (USDA) en el Bosque Nacional del Caribe El Yunque.



OH MY GOD! That’s no weather balloon!” -Gulf Breeze UFO eyewitness.


Puccinia sp. in grass blade.
Photo by JD Smith.







Red Thread by Laetisaria ficuformis.
Photo by JD Smith.






Chlorophyllum molybidites Photo by Angel Nieves-Rivera.



Marasmius oreades fairy ring.
Photo by IR Evans.





Marasmius oreades basidiocarps.
Photo by IR Evans.






Physarum cinerea in grass blade.
Photo by JD Smith.