The Walleye is basically a moving wall that goes back and forth to try and impede your progress. It has spikes on the sides, as well as on the top, which will hurt you if you touch them. However, the front and backside of the Walleye are perfectly safe to touch, so you don’t need to worry about them. They are pretty much invincible, unless you had an invincibility item yourself. You can also stun them for a short time by hitting them with a projectile or with the Cat Suit’s claw attack.