That zing in your teeth from a cold treat? Blame this ancient armored fish

This illustration depicts the early jawless vertebrate Astraspis being attacked by the sea-scorpion Megalograptus in dark, shallow waters. Both animals likely had tooth-like scales on their bodies that would have allowed them to sense things in the waters around them.

The sometimes uncomfortable sensations we feel in our teeth may be an evolutionary holdover from the scaly exteriors of ancient armored fish.

(Image credit: Brian Engh)