An abnormal specimen of Pleurobranchus peroni ?

This strange specimen looks like Pleurobranchus peroni, but the mantle surface is very strange, without really the classical small tubercles each outlined by a polygon...

Christophe Cadet

Etang salé on a Rocky coast, less 1 m, 20 September 2009, size : 30 mm

Detail of the mantle surface

The underside of this specimen,

The two tentacles (a) are formed from the rolling of the tissue into an open tube.

The foot (b) matches the mantle colouration but is consistently paler and is unspotted