With its resemblance to a tree trunk, scientists initially suspected it was some kind of extinct tree when its fossils were first unearthed in 1855. The tubelike structures in the fossils are wild and varied, unlike the structures in modern fungi, which are more ordered, SciAm noted. There were also no detectable traces of chitin, a chemical that makes up the cell walls of all known fungi. “No matter what,” Boyce told SciAm, “it’s something weird doing its own thing.”Cooper, however, remains adamant that the Prototaxites are too “fundamentally different” to shove it into the category of fungi. And so, according to Vivi Vajda, a paleobiologist at the Swedish Museum of Natural History, the “next step would be to find other fossil life forms with similar chemical fingerprints to trace this enigmatic life form through the tree of life,” she told Science.