The holothuroidea or sea cucumbers are animals with a small interior bone structure, which is why they are rarely found in the fossil record in the form of complete examples.
240 million years ago, far different from the appearance and relief we see today, in a place not too far from the current coast of Tarragona, there was a lagoon, a small inland shallow sea protected from the waves and trapped between a coral reef and the coast, and full of life.