Around 400 million years ago, the Earth was going through a profound change: life that had already spread in the seas slowly began to conquer the land. Even before trees evolved, landscapes were dominated by columnar, phalli-like life forms that grew up to eight meters into the sky. They appeared around 410 million years ago and were probably the largest land organisms until their extinction around 360 million years ago. Ever since their trunk-like fossils were discovered in 1843, science has been puzzling: What exactly were these terrestrial giants, dubbed Prototaxites (German: early yews)?
