Vestigial Structure

Vestigial Structure (Darwin-tubercle) 

Vestigial structures refer to the body structures our ancestors acquired that have lost some or all of their functions with evolution. These structures are assessed as vestigial by comparing them with homologous features in related species. Some vestigial structures grew unfunctional due to a changing environment, others because they became too harmful. They can be behavior patterns, anatomical structures, or even biochemical processes. A human example is the ear structure called the "Darwin's tubercle".