Smittina crystallina is an encrusting bryozoan that forms small, round silvery patches. Autozooids are oval to hexagonal and convex. They are 0.4-0.5 by 0.25-0.3 mm.
In the British Isles, S. crystallina is known off Wick, Shetland, the Hebrides and the western approaches to the English Channel, and from the continental shelf edge of the Bay of Biscay. Outside of British waters it occurs in the Mediterranean. It has been recorded from the Gulf of Cadiz, the Alboran Sea, the Strait of Gibraltar and in the Gulf of Lions.
The species is able to colonise hard substrates, especially shell and the cold-water coral Lophelia. It occurs in deep offshore waters. It has been reported from between 110-523 m in the Gulf of Cadiz.