Eater of Worlds is a large worm-type enemy that travels through tiles, and is made up of multiple sections that can each attack separately when cut off. To defeat it, every section must be brought down to less than two body parts to be killed (the smallest possible section is a head and a tail with no body pieces). Due to how helpful Corruption gear is, this will probably be the second boss faced in worlds that have Corruption, rather than those who have Crimson.