Aetea sica occurs on all British coasts and is reported to be presenting many parts of the world, except polar waters. The species ranges from the lower shore and subtidal waters, down to about 80 m, and occasionally deeper.
Aetea sica colonises a range of substrates including algae as well as hard substrates. The colonies are white in colour. They are composed of creeping, branching stolons, made up of tubular zooids which rest against the substrate at the proximal end (closest to the colony origin), and rise into a free erect portion at the distal end.