Other species of crinoids and corals emerged in the Mesozoic, following the Permian-Triassic extinction - but never again have we seen them together in a symbiotic relationship.
It's also unclear what benefit the crinoids gain from a relationship with coral, but one interesting thing did emerge: unlike the Paleozoic corals, the new specimens did not modify the structure of the crinoids' skeleton.The Paleozoic fossils of symbiotic corals and crinoids involve corals that have a calcite skeleton, such as Rugosa and Tabulata.
If these corals don't modify the host, and leave no fossil record, perhaps they have had a long relationship with crinoids that has simply not been recorded.