Bone resorption. Computer artwork of an osteoclast (green, bone-removing cell) destroying a piece of bone. This process, known as bone resorption, is a normal part of the continual rebuilding of a human skeleton. It can also get out of control and lead to excessive bone loss, such as in osteoporosis. The osteoclast has a ruffled edge (bottom) that is attached to the bone and which secretes acids and enzymes to dissolve the bone mineral and remove the collagen (connective tissue). This osteoclast is eating through a bone trabecula, part of the honeycombed structure of cancellous (spongy) bone. The other cells (osteoblasts) build bone tissue.