Among the many arthropods we share our home with are dermestid, or carpet, beetles (Coleoptera: Dermestidae). These beetles and their larvae feed on fur, horns, silk and are considered pests, but we haven't noticed any damage that we could attribute to them.
Dermestids are quite common in our basement. The adults can fly, but I have never seen them actually flying around, perhaps because they only fly short distances. They tend to appear out of nowhere, as did this particular individual last nite on my computer desk. It was crawling on a stack of papers while opening and closing its wings. I noticed that an upside down dermestid beetle rights itself up by opening its wings and pushing itself up.
As you can tell from the picture above, this individual was about 2 mm long. If I am not mistaken, it is Anthrenus flavipes, the furniture carpet beetle (correct me if I am wrong).
Here is how you can use dermestid beetles to clean the skeletons in your closet!
Correction added 9 April: I was mistaken. The pictured beetle is Anthrenus verbasci. See the comments by Andreas Herrmann below.