Purple Snail (Janthina janthina)

Possibly photographed by Jorapache.
Snails are hermaphrodites (both male and female).  Their amorous advances to each other involve “traumatic secretion transfer“—that is, blasting potential mates at close range with “love darts“—sperm covered in psychoactive mucus.  Understandably, neither party is particularly keen to play the female role.
photo source: Image from Imgur