What is this very tiny (3mm) centipede-like insect?
That is a dermestid larva. A beetle from the family Dermestidae https://en.wikipedia.org/wiki/Dermestidae, common name, skin beetle. They eat dried skin, or flesh, and are generally the last insect to feed on a carcass. They are the bane of insect collectors, because they eat dried insects right off the pin.