Blah blah blah giant fungus overlords
Mystery fossil turns out to be giant fungus

Excerpt:

Scientists have identified the Godzilla of fungi, a giant, prehistoric fossil that has evaded classification for more than a century, U.S. researchers said on Monday.

A chemical analysis has shown that the 20-foot-tall (6-metre) organism with a tree-like trunk was a fungus that became extinct more than 350 million years ago, according to a study appearing in the May issue of the journal Geology.

Known as Prototaxites, the giant fungus originally was thought to be a conifer. Then some believed it was a lichen, or various types of algae. Some suspected it was a fungus.

"A 20-foot-fungus doesn't make any sense. Neither does a 20-foot-tall algae make any sense, but here's the fossil," C. Kevin Boyce, a University of Chicago assistant professor of geophysical sciences, said in a statement.

[...]

Samples of the giant fungi have been found all over the world from 420 million to 350 million years ago during a period in which millipedes, bugs and worms were among the first creatures to make their home on dry land. No animals with a backbone had left the oceans yet.

The tallest trees stood no more than a couple of feet (a meter) high, offering little competition for the towering fungi.

Plant-eating dinosaurs had not yet evolved to trample Prototaxites' to the ground.