This tiny dorid is fairly common (once you figure out where to find them).  They tend to feed on red encrusting sponges, so look for those in the intertidal, highsubtidal zones and then look for what may appear to be mere blobs.  Most often these individuals have their gills and rhinophores withdrawn, making them even more difficult to see.  To find one away from its host sponge is uncommon; a few of those wanderers are pictured here with their rhinophores and branchial plume out.  Note: the rhinophores of the Rostanga pulchra are unusual in shape and this is one of the features that differentiates it a similar species, the Red Aldisa, Aldisa sanguinea. They are usually less than one inch — or 25 mm. A couple of the individuals documented here were less than 12 mm.   Both of these red dorids can occasionally be found in lighter colours and a light yellow-orange animal is pictured here.  Check out the Sea Slug Forum for further information and photos.