Cavern Crawlers (Cave Mob) and Potion of Illumination

This spider like mob crawls on the floor, walls, and ceiling of dark caverns. It evolved to live in dark tunnels and it hates any form of light. If you run out of torches, I'd say you should follow them back home because it's dangerous to venture in the dark. If you kill it, you get 1-2 crawler legs. If you put Glow berries (found in Lush Caves) in the brewing stand you get a "potion of illumination." The potion will make you into a light source for a limited time and Cavern Crawlers will stay away from you.