Question

Structures that appear to have no function for the organism but probably had a function in an ancestral organism?

Answer 1

I believe these types of structures are called vestigial structures. Vestigial structures are body parts that seemingly have no purpose or function in the current form of an organism of the given species. Examples of such structures in human include; the muscles of the ear, the appendix, the tail bone, body hair, wisdom teeth among others. These structures are often homologous to structure that are functioning normally in other species and for this reason they can be considered evidence for evolution.