430 million years ago, towering life-forms known as Prototaxites emerged from the ground, reaching heights of up to 26 feet and growing trunks up to 3 feet wide. When the first Prototaxites fossil was unearthed in 1843, it was mistaken for an ancient rotting conifer. But trees didn’t yet exist during the Silurian period, so what exactly was this thing taking over the ancient supercontinent of Gondwana?