Enamel is the outer layer of your teeth and is generally white to whitish-blue-gray, as well as somewhat translucent, according to dentist Harold Katz, DDS, founder of The California Breath Clinics.

The roughness comes from tiny, tooth-like spikes called denticles, which provide the coelacanth with protection against rocks and predators. The scales are a steely blue-gray in color and bear ...