Ancient three-eyed sea beast breathed through its bottom!

Experts in Canada have discovered fossils of a 500-million-year-old predator that lived in the sea.

Not only that, it also possessed some rather, err, unusual features.

It had three eyes, spiny claws and scientists think it breathed through its... bottom!

The discovery was made on the Burgess Shale - an important rock formation and fossil hotspot found in Canada's Rocky Mountains.

Palaeontologists at the Manitoba Museum and Royal Ontario Museum (ROM) made the discovery, which was published in the Royal Society Open Science journal.

The new find has been named Mosura fentoni and was about the size of an adult's index finger (around 8cm long).

According to researchers, it had three eyes, spiny claws, a circular mouth lined with teeth and a body with swimming flaps along its sides.

Experts say these features show it to be part of an extinct group of sea predators known as the radiodonts.

However, it also had a feature not seen before - an abdomen-like body region made up of multiple segments at its back end.

Joe Moysiuk, Curator of Palaeontology and Geology at the Manitoba Museum, who led the study explained: "Mosura has 16 tightly packed segments lined with gills at the rear end of its body."

He added that having respiratory organs at the back end of the body is similar to that found in modern radiodont relatives such as horseshoe crabs, woodlice and insects.

Although it's not known exactly why this was the case, scientists think it could have allowed it to capture more oxygen from its environment, or to survive in lower-oxygen environments.