Schizomavella sarniensis is an encrusting bryozoan that forms extensive nodular sheets, composed of a single layer of autozooids. Colonies are red in colour. Autozooids are quadrangular to polygonal and convex. They are 0.60 by 0.25-0.45 mm.
The precise geographic range of S. sarniensis is uncertain, owing to former confusion with other Schizomavella species. It is currently known to occur from Salcombe, Devon, from the western end of the English Channel, Galicia and from Santander, northern Spain.
The species is able to colonise hard substrates in offshore habitats.