Sheepshanks is a small lunar crater located near the northern edge of Mare Frigoris. Due south on the opposite shore is the prominent crater Aristoteles while to the north is C. Mayer. Sheepshanks appears somewhat oblong due to foreshortening, but it is actually nearly circular. The inner walls slope down to a ring of material around the inner floor. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On the Moon they are named after deceased scientists, polar explorers, astronauts or cosmonauts.