What it was
A pale column with no leaves and hardly a branch, standing over plants that only reached your shin. The thickest trunks ever found are about a meter across, wider than your front door. For roughly 40 million years it was the biggest living thing on land.
How tall
Nobody knows. Not one has ever been found standing. The longest ever dug up was a fallen log 8.83 meters long, nearly as long as a city bus.
Still a mystery
Since the first one was dug up in 1859, scientists have said what it was eleven times: a tree, a seaweed, a fungus, a lichen. Inside there is no wood, only tangled tubes. In 2026 a team in Edinburgh found the tube walls had no chitin, the stuff a fungus builds with. It may belong to a branch of life that has no survivors. Not everyone agrees.