An unusual-looking sea creature has washed up on a beach in Hawaii. The animal was found on Lanikai Beach on the island of Oahu and was captured on camera by Tiphareth Aquarian, before being returned to the ocean.

According to Megan Porter, an assistant professor of biology at the University of Hawaii at Manoa, the bizarre creature is an argonaut, a type of octopus.

Also known as a paper nautilus, the octopus is normally found in the open ocean, where is feeds on small crustaceans, molluscs and jellyfish.

Argonauts use tentacles to grab hold of prey and drag it towards its mouth, where it is able to bite the prey and inject it with poison from its salivary gland.

The argonaut that washed up on the Hawaiian beach is a female as male octopuses don't have shells.

Porter said the octopus may have been drawn to the beach by lights.

"What the picture shows is a shell that the females in this particular group of octopus makes themselves as a protection for their eggs. So it's an egg case that they carry around with them to protect their eggs while they're developing," Porter told Hawaiian news site Khon 2.

"I don't think that they come in close to shore very often, or they're out at times when people aren't out in the water, so to have one wash up on shore where people can actually see it, it's actually rare."

The argonaut, a type of octopus Tiphareth Aquarian