Top 10 new species of 2015: Cartwheeling spiders, 'chicken from hell' and a giant stick insect celebrated in the year's first official list (14)

The mysterious mushroom-shaped 'living fossil'

Name: Dendrogramma enigmatica

Location: Deep sea off Point Hicks, Victoria, Australia

What is it: A potentially new phylum of deep sea animal

Why it made the list: Dendrogramma enigmatica and a second new species, D. discoids, are multicellular animals that look rather like mushrooms, with a mouth at the end of the 'stem' and the other end in the form of a flattened disc.

The best information suggests that they are related to the phylum Cnidaria (jellyfish, corals, sea anemones and hydras) or Ctenophora (comb jellies) or both, but the new animals lack evolutionary novelties unique to either and could be an entirely new phylum.

They also resemble fossils from Precambrian time, perhaps making them living fossils of sorts. The mystery surrounding this animal accounts for its name, and its relationships are likely to remain enigmatic until specimens can be collected suitable for DNA analysis.

The new animal is small, with a stalk less than a third of an inch (8 mm) in length and a 'cap' that measures less than a half-inch (11mm) across. It was found on the sea floor, at a depth of about 3,200 feet (1,000 meters), off Point Hicks, Victoria.

This strange mushroom-shaped species is actually an animal rather than a fungus and is found living on the floor of the deep ocean