The Lavae Tooth is an item exclusive to Don't Starve Together. The Tooth is dropped from a hatched Lavae Egg. Picking up the Tooth will cause the Lavae that spawned from the same egg to follow you, much like Chester's Eye Bone and Glommer's Flower. Dropping the Tooth on the ground or leaving it in a stationary container will cause the following Lavae to stay by that location.
If Krampus steals this item, the lavae will start to follow Krampus.