At a crinoid garden that I have been working for a couple of years, I found this curious example of an epibiont on an epibiont.
First, a trepostomate bryozoan found its home, then some cornulites worm tubes found the bryozoan inviting.
Finally, the sponge.
When it was alive, it had to have been pretty cool looking with the worms sticking out of the sponge.
Since, it was found at one of my crinoid “gardens”, here is a double from the same locality. I have pulled about 50 crinoids from this site(too lazy to check my notebook), and the Archaeocrinus sp. out number Pychnocrinus sp. by a substantial majority(again, too lazy to check my notebook), So these are probably Archaeocrinus sp.
Many of the crinoids at this site appear to be weathered, but they are from fresh exposures??? They are found in a thin lens of mudstone within a calcarenite/calcirudite. They are early Late Ordovician. Some researchers postulate that the abrupt changes in facies in the Central Kentucky region is due to weird structural crap associated with tensional forces at the close of the Taconic Orogeny to the east.
So, that leaves me wondering… were these critters left high and dry in their shallow lagoon/inlet by a regression, and then covered by a transgression??? It seems plausible. They could have laid there for months, or longer, since there were no land critters to pick at the carapaces.
Do you have another scenario??? Let me know.
Anyway, here is the double.