Communal Slimefort
The communal slimefort managed to come about when its ancestor, the slimefort wormfort, evolved a more cost effective solution to constructing their slimeforts. This solution was to grow in groups, with each individual member and its fort supported by those of its kin. The resulting communal forts offered both increased stability as well as requiring noticeably less slime - and thus energy - to produce, and over time led to larger and larger forts being built. The average colony is typically composed of 14 or so members, though older, larger forts can have as many as 24 individuals.
The juvenile stage of the communal slimefort is nearly identical in appearance to that of its ancestor, the slimefort wormfort, though one notable difference is that they are only able to reach half of their length. When the time has come for a juvenile to mature and turn into an adult, it will seek out either a lone adult or a communal slimefort colony with which it can then build its own slimefort right up against. However, if there are no other adults to be found, they will instead create a slimefort in a manner similar to that of its ancestor and then hope for more juveniles to find and build their own slimeforts next to it. If a colony has a vacant empty spot left over from the death of one of its own members, a juvenile communal slimefort will simply enter the pre-made hole and remake for its own needs instead of needlessly expending excess energy to construct a new slimefort from scratch.