A benthic ctenophore from the Philippines

Dear Mabel,
This is 'slug' is not a mollusc. It is a very strange member of the phylum Ctenophora. The most common members of this phylum are small planktonic animals called Comb Jellies which have a pair of long branches tentacles for catching their prey. The platyctene ctenophores are a small group which no longer swim, and are flattened to look much like a slug or flat worm. Some live directly on the sea floor while others live on plants or sessile animals. They can be recognised buy the pair of branched tentacles which usually have a pointed sac in which they can retract - your 'twin peaks'.

Your animal is probably a species of Coeloplana. Although not a real sea-slug, these are very interesting animals. They are seldom photographed and usually misidentified as strange flat worms.
Best wishes
Bill Rudman