Odontodes, or dermal teeth, are hard structures found on the external surfaces of animals or near internal openings. They consist of a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel, a structure similar to that of teeth.
Dermal spines, like odontodes, are robust elements located on the outer surfaces of animals or near internal openings. They consist of a soft core encased in dentine and protected by a mineralized substance similar to teeth.