Here we go.
This is a pretty durable creature, except for the parts of its blue flesh not covered by rock. When it wants to eat something big, it grabs it with its arms and holds it near its mouth. Because it only eats bones, it sprays an acid over the specimen that melts down to the bone. He then, obviously, eats it.
It also has very bad eyesight and is weak in the back, just in case it attacks.