Echinoids have lived in the seas since the Late Ordovician, about 450 million years ago, which is about 220 million years before dinosaurs appeared.

How old is the sea urchin fossil?

The sea urchin fossil found by a USC team had been buried in a rock formation that dates back nearly 270 million years.

What type of fossil is echinoids?

Echinoid fossils are the fossilised remains of sea urchins, spiny marine invertebrates that live on the seabed. Humans have been interested in these fossils for millennia, have considered them lucky, have imbued them with magical powers and linked them to their deities.