Great fleas have little fleas…
November 14, 2011 § Leave a comment
… upon their backs to bite them.
And little fleas have lesser fleas, and so ad infinitum.
Wired Science has an example from 50 million years ago: a mite on the back of an amber-encased spider. Sadly, there was probably no biting involved — the mite was probably just using the spider as transport.