Bass is Dr. Maura Isles' Geochelone sulcata, or an African spurred tortoise. Maura named him after William M. Bass, the forensic anthropologist who founded the famous body farm. Bass eats British strawberries, spinach, and other organic vegetables.

Maura is defensive when it comes to Bass; every time Jane calls Bass a turtle, Maura retorts that he is a tortoise.

Bass was shown to have some health problems resaulting in a loss of appetite later on.

In Family Matters (Season 5 Episode 18), Jane says "seeing Bass at the zoo" as a way for Maura to cheer herself up after her recent breakup. This suggests that Bass was sent to the zoo because of the loss of appetite and has made a recovery since.