Dead cells that form over a wound or blemish while it is healing is a:

The correct answer is that dead cells that form over a wound or blemish while it is healing are known as a crust. In the context of skin healing, a crust typically refers to a dried secretion that forms as a wound begins to heal, acting as a protective layer over the injured area. This formation is a natural part of the healing process, as it serves to safeguard the underlying new tissue and help prevent infection while the skin repairs itself.

A scab is often used interchangeably with crust; however, in dermatological terms, it usually denotes a specific type of crust that results from blood clotting and drying. A pustule refers to a raised, inflamed lesion filled with pus, often associated with acne, and does not indicate the same type of healing process. A fissure, on the other hand, is a narrow, linear break in the skin, often resulting from dryness or irritation, rather than a response to a wound healing. Understanding these nuances helps clarify the specific term applied to the healing skin.