This week I'm going to continue my exploration of the alien weirdness of the phylum Echinodermata and put the spotlight on the class Crinoidea, better known as sea lilies.
Although they resemble plants, crinoids are animals with calcareous exoskeletons that live attached to the sea floor by a root like hold-fast. The feather-like pinnules on their arms beat to generate a feeding current that draws food particles into their mouths, which are situated atop a calcareous cup called a calyx. The stalk, which extends from the seafloor to the calyx consists of calcareous discs, called ossicles that fit together like a tube of Certs.
While crinoids are extremely abundant as fossils, they are rarely preserved intact. After death, the animal's exoskeleton quickly falls apart so that only bits and pieces are preserved. The ossicles that make up the columnal are the parts that are most commonly preserved.
Indeed, crinoid ossicles are so tremendously abundant that entire limestone formations are composed entirely of them. The Mississippian age (Late Carboniferous) Lodgepole Formation that crops out in the Little Rocky Mountains of Montana forms limestone cliffs up to 200 metres thick that are composed almost entirely of crinoid ossicles. This sort of rock is so common it even has a name: crinoidal grainstone, and is shown below.
The vast abundance of crinoids that must have covered the sea floor in Earth's distant past, sufficient to build up hundreds of metres of thickness, is absolutely mind-blowing. Sadly, though, for all the abundance of the ossicles, calices are rarely preserved intact - I've been hunting for one for more than fifteen years and still haven't found one yet. When they are preserved, however, a fully articulated calyx is an absolutely exquisite fossil:
While most modern crinoids are free-swimming and lack a stem, a stalked crinoid was observed, in recent years, pulling itself along the seafloor. The idea of stalked sea lilies moving lends an even deeper Lovecraftian shade and are makes them so bizarre as to be the stuff of nightmares. Imagine if they possessed an alien intelligence. Imagine if they had a purpose...
It's time to break out my campaign binder and start making up another monster, I think.
Welcome Back to the Labyrinth
"We have been away far too long, my friends," Ashoka declared, his face lit by the eldritch green glow of his staff. "But we have finally returned to the labyrinth whence our adventures first began."
"Just imagine the treasures that lie within," said Yun Tai, flexing his mighty muscles. "Wealth enough to live in luxury the rest of our days."
"And arcane artifacts of great power," added Ashoka his words dripping with avarice. "All ours for the taking!"
"Umm...guys?" Nysa interrupted. "Do you hear something dripping?"