In this map, the elder brain is a living organism that grows in underground caverns covering the walls in its growing flesh. The elder brain produces the eggs of the mind flayers that tend to its needs.

The mind flayers hatch from the egg hatchery in the central chamber. The tadpole (slad tadpole stat block) than makes its way to the cavity filled with greenish fluid to grow into a grick. The grick eventually wriggles out of the fluid into a pod to grow into a mind flayer. The pod is used by the mind flayer as a place of rest and regeneration for its entire life. The mind flayers cannot live without the entity and the entity cannot live without the mind flayers.

Once in a while, instead of a tadpole, a small brain is hatched (intellect devourer). The brain eventually grows into another elder brain and mind flayers take it to form another colony.