Xyloplax is thought by some to represent a newly discovered sixth class of echinoderms - and by others to be an asteroid.
Nearly, every class of traditional material has an ODNS counterpart.
Reef mounds (bioherms) provided the Silurian seafloor with an organically constructed microtopography featuring zonations of segregated brachiopods, gastropods (class of mollusk containing present-day snails and slugs), crinoids (class of echinoderm containing present-day sea lilies and feather stars), and trilobites.
The Wenlock Limestone is one of the best-studied Silurian formations of the world and is noted for its abounding variety of excellently preserved fossils: brachiopods (lamp shells), corals, trilobites, clams, bryozoans (moss animals), and crinoids (class of echinoderm that includes present-day sea lilies and feather stars).
And some of those things that you saw in that earlier picture were extinct classes of echinoderms.
All classes of echinoderms that were present during the Cambrian, except for the Crinoidea, subsequently became extinct.
Three species of three different classes of echinoderms had COI-5P successfully amplified and sequenced, albeit other authors acknowledge that amplifying COI-5P from echinoderms remains a challenge, probably due to the unsuitability of the primers used or to DNA degradation [ 10].
Among the remaining deuterostome phyla, intracellular Hbs have been reported in two of the 5 classes of echinoderms [ 84, 85], and we find a putative globin in the recent assembly of the genome from the sea urchin Strongylocentrotus purpuratus, which belongs to another class.
Blastoid, any member of an extinct class (Blastoidea) of echinoderms, animals related to the modern starfish and sea lilies, that existed from the Middle Ordovician to the Late Permian periods (from 472 million to 251 million years ago).
There are, I think, six or seven classes currently of echinoderms; but back in the Cambrian there were about twenty-five or thirty.
The different classes of the echinoderms now are things like the asteroids, which are the starfish; the holothuroids, which are the sea cucumbers, and so forth.
