Aplustrum amplustre | ©Kévin Bourdon (Ile de la Reunion)
The commonly known as Pink Bubble, Swollen Bubble, Royal paper bubble, Ship’s flag shell or Swollen bubble, is a marine snail of the species Hydatina amplustre, Syn. Aplustrum amplustre (Gastropoda - Aplustridae), widely distributed in the Indo-Pacific.
This species is easily recognized by its thin, strongly inflated shell marked with broad flesh-colored bands outlined in black. The animal is translucent cream and too large to fit in the shell [source].
Hydatina amplustre is a nocturnal species and vision is not the most important sense, so the two black spots you see in the photo are the ocelli, the visual organs that only distinguish light and dark.