Plumaster ophiuroides, 11 cm with small Tropidaster pectinatus

In one of the fossil forums I visit, fellow collector Tarquin Bolton recently showed a fabulous
fragment of another starfish that made me re-assess my specimen and another acquisition
of a complete specimen from an old collection that I have treated myself to in 2012, shown
above.

The specimen painstakingly prepped by Tarquin, with great patience & skill removing grain
by grain of matrix with a prep needle and a modified dental descaler in about 150 hours,
shows an amazing fine structure of small ossicles similar to regular echinoids and enables
the specimen to be attributed to the genus Plumaster, more specifically to the species
Plumaster ophiuroides WRIGHT 1863, which has also been written about by
Prof. Andrew Gale (Portsmouth University) in a 2010 paper.

Sure enough, when I looked at the complete specimen above under magnification, I also
saw these structures, and thus it is not a Luidia, but also a Plumaster and so is the fragment
I had shown earlier.

It seems now that Plumaster is much more “common” (relatively speaking, they are still
extremely rare in absolute terms !) than Luidia, and is also quite often associated with
Tropidaster, as is the specimen shown at the top.

Plumaster is in fact, unlike Luidia (which Hans Hess placed in Solaster in 1955), not a
“true” sun star belonging to the Solasteridae family of starfish, but belongs to the
Plumasteridae, a family erected by Andrew Gale as recently as 2011.