@smokeythecat has it right. Note that, despite the use of terms like 'stem' and 'sea lily', these are animals not plants, and loosely related to starfish and sea urchins. The 'stem' is more usually called the 'columnal'.
Crinoids of this type first appeared in the Ordovician period around 480 million years ago and, although as said they aren't extinct, there are no known fossils which are more recent than 200 million years (and not from America).