Lophophorates Accepted Hyoliths As One Of Their Own

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Hyoliths are ancient invertebrate animals from the Palaeozoic Era that trawled the seafloor about 500 million years ago. These soft-tissue animals lived in small, calcareous, conical shells that had two curved supports known as 'helens'. This extinct species did not resemble any of the extant groups and it had been unclear whom they should be grouped with.

Scientists have long considered them as mollusks but also resembled sipunculids and annelids. Some scientists had even classified hyoliths as 'Incertae sedis' which is Latin for 'we don't know'. Now, after studying over 1,500 well-preserved fossils from the Burgess Shale in the Canadian Rockies and the Spence Shale in Idaho and Utah, scientists have finally grouped them together with 'Lophophorata'. This group also includes Bryozoa, Brachiopoda, and Phoronida.

MSN reports that these benthic (those who live at the bottom of a sea) animals used tentacles and spines (which are known as Helens) to trawl across the seafloor. According to a research published in Nature online on January 11, 2017, the living members of the lophophores family include lamp shells and horseshoe worms. They have soft bodies, a ring of tentacles around their mouths, concealed U-shaped guts, and a conical shell encasing.

The Science News claims that the tentacles protruding from the hyolith's shell are part of feeding organ called a lophophore. It was found that Hyolith fossil specimen had six tentacles of the lophophore feeding organ and two spines. Grouping them with lophophorates has settled a long-standing debate of paleontology - one which had been going on for almost 175 years.

It is believed that hyoliths lived on the ocean floor for 280 million years - during the Cambrian period (543 million to 490 million years ago). Shaped like ice cream cones with lids, they were about 1 cm long, had cone-shaped shells with a shorter and rounder top shell.