Diplograptus floating in Cambrian seas. These colonial animals are known from Middle Cambrian to Lower Carboniferous fossils. The name graptolite comes from the Greek graptos for written and lithos for rock —
written on the rock. And they do look a bit like scratches or calligraphy, but more so like primitive plants. I confess that when I found my first graptolite fossil, I had assumed this was a plant group, then looked them up and low and behold... aquatic sea animals!
