Lump

Lumps remain stationary in one spot and shoot a spread of three shots towards Isaac when he comes within range, then they burrow underground and resurface in a different part of the room. If they resurface in range to shoot at Isaac, they will do so incredibly quickly before burrowing underground again.

Lumps will also burrow underground to reappear elsewhere if Isaac doesn't approach them for a short period of time.

Notes

When a Lump is a Green or Purple Champion, it can be seen teleporting around the room while burrowed.

Variations

Tar Boy

Tar Boys occasionally fire a short-ranged spray of shots towards Isaac that leaves behind slowing Black Creep. It can also burrow underground and resurface in a different part of the room, much like the Lump. However, it is only able to resurface in areas that have Black Creep and it will prefer to resurface close to Isaac.

If Isaac is standing on Black Creep, Tar Boys can launch a fountain of tar shots straight upwards out of the Creep where Isaac is standing/ create a Nerve Ending-like tentacle directly underneath Isaac. This can also occur with Black Creep spawned by other enemies such as Gushes.

Gallery

Tar Boy's tentacle attack.
Concept art for Tar Boy.

Trivia

Tar Boys were added in Booster Pack #4.
Lumps had a radically different appearance in the original Binding of Isaac.
Previously, Lumps appeared as Light Brown in the Scarred Womb. As of Booster Pack #5, Lumps are now red in this environment.
Tar Boy is a reference to the Newgrounds animation of the same name.

Bugs

Bug!	If you stun a Lump at the same time that it burrows underground, it will cause their sound effect to repeat continuously for a few seconds.

Bug!	If a Lump spawns as a Light White Champion, when the Lump burrows underground, its Eternal Fly will rapidly teleport around the room, potentially resulting in unavoidable damage.