This unusual little nudibranch has been occasionally sighted at low tide in the shallows of Spencer Park. According to the expertsDr Richard Willan& Steve Smith this is an Aeolid,   Spurilla braziliana.Until now ,Coff's harbour was the southernmost sighting recorded.

I haven't been able to find any information on this particular species but looked at many others in the Spurilla  sp. on the Seaslug Forum site.