Sponge-like fossil could be Earth’s earliest known animal

Crystalline tubes seen in rocks (left) might have been formed when the collagen-like skeleton of an 890-million-year-old sponge decayed and fossilized. Some modern sponges have internal scaffolding (right) that resembles the shapes in the rocks.
Credit: Elizabeth C. Turner

“Fossil discovered in northwestern Canada could rewrite the early history of animal life — but some palaeontologists are not convinced it’s real.”

“Most major groups of animals — including arthropods, molluscs and worms — first appear in the fossil record during the Cambrian explosion, 541 million years ago. But according to a paper published today [28 July 2021] in Nature, sponge fossils from northwestern Canada could be 350 million years older, significantly pushing back the date of Earth’s earliest-known animals.”

“It’s such a big claim that you really have to eliminate all the other possibilities.”

(https://www.nature.com/articles/d41586-021-02066-9)