Divers in Australia have captured rare images of the Pyrostremma spinosum, or pyrosome, sea creature off the coast of Tasmania.

It is so rare it has been dubbed the 'Unicorn of the Sea' and can grow up to 30 metres long - the equivalent of two double-decker buses laid end-to-end.

Its hollow, translucent, cylindrical body is made up of thousands of tiny clones called zooids that pull water through its tubes and feed on plankton before pushing the filtered water back out.