Alien-like mushroom-shaped creatures have been discovered in the depths of the ocean off the Australian coast.

Scientists said two species of the unusual life form were found that could not be placed in any existing group of organisms.

Scientists suspect they are related to ancient extinct life forms that lived 600 million years ago. Credit: Public Library of Science/ PLOS ONE

The animals, named Dendrogramma, consist mainly of an outer skin and inner stomach, separated by a dense layer of jelly-like material.

Scientists suspect they are related to ancient extinct life forms that lived 600 million years ago and may have been a failed early attempt at multicellular life.

They consist mainly of an outer skin and inner stomach separated by a dense layer of jelly-like material. Credit: Public Library of Science/ PLOS ONE

The organisms were discovered in a collection dredged up in 1986 from depths of 400 and 1,000 metres (1,312 and 3,280 feet) on the southeast Australian continental slope.

Only now have the researchers isolated the two species of Dendrogramma, described in the latest edition of the Public Library of Science ONE journal.

The species have been named Dendrogramma enigmatica and Dendrogramma discoides. Credit: Public Library of Science/ PLOS ONE

The species have been named Dendrogramma enigmatica and Dendrogramma discoides.