Cast a net back 450 million years ago to the Ordovician Era, and you wouldn't capture anything more than the ancestors of millipedes and worms.
However, you might notice 29-feet-tall (8m) trunks without branches or leaves, towering over a landscape of newly-evolved vascular plants.
These trunks, which have been found as fossils all over the world, are now strongly believed to be mushrooms — giant fungal towers that mean the kingdom of fungi produced the first giant land organism.
The idea of a 'fungal forest' is one that's often reproduced in fantasy and science-fiction writing. Mushrooms are extremely attractive to the human eye and imagination. From Super Mario to the visual art in James Cameron's Avatar, why have trees when you could have mushrooms?
The Prototaxites Mystery
In 2008, a large trunk-like fossil was uncovered in Saudi Arabia. Identified as a Prototaxites , it presented more evidence that these strange spires from the mists of evolutionary past are mushrooms.
A Living Ecosystem
mycelia have been found invading nearby plant tissue, hinting at early ecological interactions.