Vestigial structures are remnants of features that served a function in the organism’s ancestors. These “leftover” structures provide little to no purpose to the organism or any of its life functions. However, these organs offer significant evidence supporting evolution and common ancestry. For example, pelvic and leg bones found in snake skeletons serve as remnants of their walking ancestral counterparts. Blind fish species that retain primitive eyes show the evolutionary adjustment to their environment. This hog, as well as other hooved species of pig, possesses a dewclaw on its foot. Also referred to as a “Dog’s thumb” is a vestigial digit that oftentimes does not come in contact with the ground. This digit is found in dogs, deer, and other mammals, but they are presently functionless.