Which of the following probably best expresses the “puzzle” mentioned at the end of paragraph 2?

What exactly does one slipper limpet do that affects another slipper limpet’s transition from one sex to another?

How close must two slipper limpets be to each other for sexual reproduction to take place?

Since any slipper limpet can simultaneously be both male and female, can sexual reproduction take place without the presence of another slipper limpet?

How did the slipper limpet evolve into an animal that can change its sex from male to female?

If two male slipper limpets are close to each other, why does only one of them make the transition into a female?