During normal bone development and fracture healing, cartilage turns into bone. Osteoclasts, a type of specialized cell, eat cartilage, provide passage for blood vessels, marrow and other bone cells. In this image of cartilage (purple and white) from a young mouse femur, osteoclasts (red) surround a blood vessel filled with red blood cells (yellow). Unlike normal osteoclasts, the cells present here have only one nucleus due to the absence of a gene involved in osteoclast development. This research program aims to understand how large bone-resorbing osteoclasts form and whether preventing them from fusing is a way to control bone loss in osteoporosis, arthritis or other conditions. This image won the 2015 Federation of American Societies for Experimental Biology (FASEB) BioArt competition.