An idea I’m toying with for a sci-fi story is a species where the individual organisms are colonies of smaller eusocial organisms. The idea initially came from “hey if a bunch of single-celled organisms can stick together and that colony eventually evolve into larger multicellular organisms, can that jump be made again?” I’ve tried to find information about this - environmental factors that could contribute to this, what these greater organisms would be like, and, possibly, could they get to a point where they could create languages, cultures, societies, etc. All I’ve found is people bringing up the idea, but not expanding on it. Any ideas for how I could get this to work from a biological standpoint?
See the Portuguese man o' war's structure
Being a colonial siphonophore, the Portuguese man o' war is composed of three types of medusoids (gonophores, siphosomal nectophores, and vestigial siphosomal nectophores) and four types of polypoids (free gastrozooids, gastrozooids with tentacles, gonozooids, and gonopalpons), grouped into cormidia beneath the pneumatophore, a sail-shaped structure filled with gas.
The Bluebottle or Pacific Man-of-War is not a single animal but a colony of four kinds of highly modified individuals (zooids). The zooids are dependent on one another for survival.
The float (pneumatophore) is a single individual and supports the rest of the colony. The tentacles (dactylozooids) are polyps concerned with the detection and capture of food and convey their prey to the digestive polyps (gastrozooids). Reproduction is carried out by the gonozooids, another type of polyp.
One characteristic you are definitely looking for is a hive mind. This would be required to develop intelligence for the large organism.
As an example, Formic fleets in Ender's Game were described to behave as a single organism. Depending on your scale, a fleet of spaceships might be called a single organism.
But rather that the central queen, being stupid as a unit but making the collective smarter the larger seems like a better fit for your description.