This egg was only available in Egg Cave's Cash Shop Park in October 2012 for the Halloween Bash.
These eggs are commonly mistaken for discarded bits of bone, a natural camouflage that keeps these eggs safe in their home, The Barrenlands. As such, people rarely find them in the wild since they tend to be overlooked.
The bone that grows out of a Sherth's head, back, and tail is actually a form of exoskeleton that they use for protection and defense. Because of this, Sherths need plenty of calcium to keep their exoskeleton growing strong, which many get from chewing bones. It's not uncommon for owners to give their Sherths leftover chicken or beef bones to keep them healthy. They are a favored pet of butchers for this reason.
Despite the tendency for wild Sherths to be secretive and territorial, a home-raised Sherth can become a very loyal companion, although still a little territorial. Many owners find that this is ok, however, and will use a home-raised Sherth to guard their homes while they are away.