The Oileacún is a quadruped with bristly, zig-zagged black and white fur, a white head with white ears and a black nose. Around the eyes, the fur is black in a mask-like pattern. The feet have three claws each, every one with pink paw pads. The maxilla is jagged. Most prominently about the dentition are two pointy teeth on the lower jaw.
Oileacúns can grow to a height of 0.4 metres at the brow and to a length of 1.8 metres from the tip of the nose to the tip of the tail. Their normal weight at that size is around 18 kilograms. They are omnivores.
Around the 7th or 8th centuries, the Oileacún, or the Orsella, as he is locally known, was accidentally introduced to Lutetii, becoming a pest raiding trash cans and being a nuisance.