The skeleton allows movement, provides support and protection for vital organs and makes blood cells. Skeletal muscles move the bones in the body. The skeletal system is made from bones and joints.

Despite their similar structure, however, not all bones are created equal: in vertebrates (including humans), the various parts of the skeleton arise from different groups of precursor cells ...

This is a magnified image of the structure of the cell wall of a diatom from marine sediment collected ... Click on the right arrow to see other skeletal structures, as well as multiple diatoms ...