squama(n = noun.animal) - a protective structure resembling a scale;
is a kind of scale
has particulars: alula, calypter

   A scale cast off from the skin; a thin dry shred consisting of epithelium. [1913 Webster]

squama, n. (pl. squamae)
1 a scale on an animal or plant.
2 a thin scalelike plate of bone.
3 a scalelike feather.

Derivative:
squamate adj. squamose adj. squamous adj. squamule n.

Etymology:
L squama