"Tauroctony" is your two-dollar word for the day. It refers to the artistic depiction of the mythic hero Mithras ritually slaying a bull (the sacrifice is called a taurobolium).
In the depiction, Mithras, wearing a Phrygian cap and pants, slays the bull, kneeling on its back with his left knee while looking away. His cape billows behind him showing its inner side. A serpent and dog seem to drink from the bull's open wound (which often spills blood but occasionally grain), and a scorpion attacks the bull's testicles. Typically, a raven or crow is also present, and sometimes also a goblet and small lion.There is general agreement that the symbolism is astrological. More details at Wikipedia.