According to CooksInfo.com, the crescent-shaped part that is attached to the flesh of a scallop is called the "coral" by some and the "roe" by others. It has a bright orange coral color.
While some choose to discard the coral on a scallop, others tend to remove it and cook it last. It is delicate and requires less cooking time. The roe tastes similar to the scallop muscle; but it's a bit more on the briny side. Some say it has a similar texture to liver. The roe of a scallop is actually its reproductive glands, or gonads. It is very perishable and, therefore, not common.