Pure-white shell with nearly invisible lateral striations. Orange operculum. P. mammilla is a species of predatory moon snail.
This species occurs in the Red Sea and in the Indian Ocean off Kenya, Madagascar, Mauritius, Tanzania and Transkei, and apparently in the Philippines.
Spotted this in about 23m of water during a day dive at the Coral Gardens dive site, Talikud Island, Samal, Philippines. It measured about 4cm long. I would've wanted to see it come out but I guess it was asleep.