They may be most famous for inspiring the animated character SpongeBob SquarePants, who lives in a pineapple under the sea.

But scientists have now discovered 12 new species of weird and wonderful sea sponges, some of which have such an extraterrestrial-like appearance that they have been described as 'alien life here on Earth'.

Others have been named for their similarities to a polar bear and a unicorn.

Their discovery has been revealed in a new study by UC Santa Barbara professor Dr Thomas Turner and research ecologist Steve Lonhart, who spotted the sea sponges while diving off Monterey Bay, California.

In total the pair documented 29 sponge species — 12 of which were previously unknown to science