Silicified Sponge – Moretiella elegans

Cretaceous

Garraf, Catalonia, Can Casanyas Castellet, Spain.

38mm silicified sponge. It is literally made of glass!

Moretiella is a genus of sea sponge best known from the Early Cretaceous of Europe but also present in the Late Cretaceous.

Paleontologists consider sponges to be among the oldest groups of modern animals.  It appears that they diverged from their ancestors in Precambrian time.  The oldest undisputed sponge fossils are Cambrian age and bear the same biomineralized skeletal structure as modern forms.  How that skeleton developed remains a mystery.