Sometimes the anterior clump is recognisable on adults when the cerata are curved over the body, but the clumps are rarely as compact as on F. auriculata.
Very long, broad-based oral tentacles, about twice as long as the rhinophores, taper to a fine point.
Length 9.8 mm. Outer Hebrides, Scotland. April 2018. Leg. D. McKay & S. Taylor.