[IC] New Crobuzon & the World Beyond

[GM Marvel]

[[...my next question is why is the swarm now several smaller swarms?]]

From the SRD:

Unlike other creatures with a 10-foot space, a swarm is shapeable. It can occupy any four contiguous squares, and it can squeeze through any space large enough to contain one of its component creatures.

It just made sense that the swarm would would stretch around the cube.  So it's still one creature. It's just stretched out into 4 squares.