Seems to be the name of a kind of coral. This would fit with the context from The Name of the Rose since Adso was describing a carved door that contained many creatures one would find in an obscure bestiary.
From The Free Dictionary: "Pliny said that the offspring of a crocotta and a lion was the leucrota (or leucrocuta, leucrocotta, or leocrocotta), which could imitate the sound of a human voice. This was no doubt the source of the later, similar claims for the abilities of the crocotta itself. The leucrota was said to be a cloven hooved animal the size of a male donkey, yet swift and fierce. Described as having the haunches of a stag; the tail, chest, and neck of a lion; and the head of a badger, its mouth was said to open back as far as its ears. Instead of teeth it had ridges of bone that could crush anything. It was said to never close its eyes and its backbone was said to be so rigid that it had to turn around to see what was behind it."
"The dog-wolf crocotta and the antelope-like leucrota were clearly meant to be two different types of animals, but because of their alleged blood relation, the similarity of their names, and their supposed ability to speak with a human voice, the authors of bestiaries often mistook one for another. This is likely the source of many of the later conflations of their reputed characteristics."