Tortotubus

Tortotubus is an early (Ordovician to Devonian) terrestrial fungus. Its growth trajectory can be ascertained from its fossils, which occur across the globe from the Ordovician to the Devonian. These fossils document foraging activities of slender, cell-wide exploratory hyphae; when these hit a source of food, they produced secondary branches that grew back down the original filament, covered themselves with an envelope, and served as pipes to shuttle nutrients to other parts of the organism. Today, mycelium with this growth pattern is observed in the mushroom-forming fungi.

== Background == The form genus Ornatifilum was erected by Burgess and Edwards in 1991 to describe tubular fossils retrieved by acid maceration from the late Silurian. It was originally intended as a form genus, to facilitate stratigraphy and environmental reconstruction; the fossils do not display enough features to classify them confidently, even at a kingdom level.