The calcaneus, also called the heel bone, is a large bone that forms the foundation of the rear part of the foot. The calcaneus connects with the talus and cuboid bones. The connection between the talus and calcaneus forms the subtalar joint. The calcaneus is a "short" bone. It is often compared to a hard boiled egg, because it has tough, hard, cortical bone on the outside and spongy, soft bone on the inside.

More Info: www.foothealthfacts.org