The pigbutt worm or flying buttocks (Chaetopterus pugaporcinus) is a species of worm found by scientists at the Monterey Bay Aquarium Research Institute. The worm is round in shape, approximately the size of a hazelnut, and bears a strong resemblance to a disembodied pair of buttocks. Because of this, it was given a Latin species name that roughly translates to "resembling a pig's rear."