Puellina bifida is an encrusting bryozoan. Colonies form broad, irregular sheets, composed of a single layer of autozooids, and can grow to 200 autozooids or more. Autozooids are oval to irregularly polygonal, convex and separated by distinct grooves. The range in size from 0.25-0.4 by 0.14-0.22 mm and have 5 oral spines.
The species is able to colonise shell substrates in subtidal offshore waters.
Puellina bifida is known to occur in the English channel, Normandy, Brittany, Guernsey, Cornwall and off Antrim in the Irish Sea. Its depth range has been recorded from 29-130 metres. Puellina bifida is similar to the Mediterranean species Puellina minima, however P. minima has only 2, rather than 4, oral spines on reproductive zooids (with an ovicell).