Odontodes, or dermal teeth, are hard structures found on the external surfaces of animals or near internal openings. They consist of a soft pulp cavity surrounded by dentine and covered by a mineralised substance such as enamel, a structure similar to that of teeth.[1] They generally do not have the same function as teeth, and are not replaced the same way teeth are in most fish.[2] In some animals (notably catfish), the presence or size of odontodes can be used in determining the sex.[3]