“Organic” anthole themed room: instead of using a rectangular room, it disrupts its edges so as to not look manmade. Then the room type is specified as anthole to stock it with ants.

Anthill: a dungeon feature found exclusively in antholes that acts as a monster spawner for ants. The ants produced will all be the same type as the anthole is, and ants will not spawn out of it when there are already a certain number of ants in the area. Eventually it stops spawning ants (perhaps with a system where it rolls every time it creates a new ant and if it fails the roll it increments an internal counter; the higher the counter gets the lower the chance of spawning more ants), or the player can prematurely destroy it by digging it.

To compensate for the extra ants spawned, antholes could no longer be packed full of ants.

Antholes contain eggs of the type of ant the room is filled with; fewer than the ants themselves.

Ants can dig and tunnel out corridors when there is an anthole on the level, eventually turning the whole level into an anthole-like network of corridors. The tunneling AI prioritizes connecting up existing corridors rather than just destroying rock indiscriminately.