Scallop
Orientation

The shell of a scallop consists of two sides or valves, a left valve and a right one, divided by a plane of symmetry. Most species of scallops rest on their right valve, and consequently, this valve is often deeper and more rounded than the left (i.e., upper) valve, which in many species is actually concave. With the hinge of the two valves oriented towards the top, one side corresponds to the animal's morphological anterior or front, the other is the posterior or rear, the hinge is the dorsal or back/top region, and the bottom corresponds to the ventral or (as it were) underside/belly. However, as many scallop shells are more or less bilaterally symmetrical ("equivalved"), as well as symmetrical front/back ("equilateral"), determining which way a given animal is "facing" requires detailed information about its valves.
punctuation:no_comma