Writhing Remains
Summons the Eater of Worms 'It'll give you worms!'
May ruin several backyards
5Dropped by
worth farming
Master Mode boss pets are the reason people go back and refight things they already beat, and this is one of the gentler ones to grind. The Eater of Worlds can be summoned on demand, the fight happens in a corridor you dug to your own liking, and each attempt is short. If you are collecting the set, start here rather than with a mechanical boss.
The pet itself is a segmented worm that trails behind you and burrows through terrain the way the real one does. Despite the name it has no connection to the worm critter or the bait item, so do not expect it to interact with either.