Aurolk appears to be a bird egg with a slightly monster-like design to its appearance having a crack along the top allowing some of its feathers to poke out from the top and a hole for its beak to stick out of. The Pokémon also has a hole in the back of its egg where its tail feathers stick out. Its feathers are bright yellow in colour while the Pokémon's beak is a peach like colour, the beak is relatively flat and quite short the tip of the upper beak has a white spot on it.
The egg itself is predominantly white in colour with splotches of a darker cream colour on it which are more prevalent towards the bottom, it also has a small golden cap on the very top that appears to be metallic. When the Pokémon moves around it tucks its beak and tail feathers into its egg and rolls around, when they're close to evolution some will kick against the hard egg shell with their feet to bounce along the ground, if they get stuck with their head facing the ground they'll peck at it until they're back upright.