A blade barnacle.
The blade barnacle was a large, herbivorous mollusk species native to Aleph III.
History and specifics[]
It was heavy and had a hard, rough epidermis. For defense, it extended dangerously sharp ridges along its top half. It looked like a boulder, except for having 20 tiny legs underneath that maneuvered it along the the ground. It ate plants trampled by its passage.
In the 2260s, blade barnacles could be found near Federation Genetics Research Station 17. Two were kept in large cages to be studied by zoologists Carver Destry and Daniel Lane.
In 2270, just as the station was being closed down, Captain Koloth led a raiding party to attempt to steal the facility's research notes and specimens. (FASA RPG - Adventure Book module: Again, Troublesome Tribbles)