Lumps stay stationary at a single spot, firing 3 blood shots at Isaac if he gets close. After firing at Isaac, they will immediately burrow into the ground and reappear elsewhere.
Lumps usually hide behind rocks in tight spaces, forcing Isaac to get close and risk taking a hit, which makes spectral tears very useful. However, it will be difficult to accept this advice while facing them in the area with rocks blocking the way.
In order to defeat Lumps quickly and prevent Isaac from dealing damage, move out of their range and keep shooting them.
- In the Afterbirth DLC for Rebirth, in Scarred Womb, Lumps' colors are light-brownish tint rather than red to match the floor's color.
- Their appearance from both the original game and Rebirth are very different to each other.