Prototaxites (pro-toe-tax-eye-teez) is a mysterious genus of life form that lived from the Silurian to the Devonian Period. Prototaxites was first believed to be a conifer-like plant, but is now believed to be a giant fungus or huge liverwort. It was up to about 30 feet tall and could be three feet wide. Prototaxities was the biggest life form on land of its time.
Prototaxites looked like a giant tree trunk with no branches or leaves. It's possible that Prototaxities was so tall so its spores could move far away so that it would not have to compete with other Prototaxities for what it needed.
Prototaxites was worldwide and died out when vascular plants took over.