C'EST QUOI LE RAPPORT? watercolor - carnet de voyages

C'EST QUOI LE RAPPORT? watercolor in my carnet de voyages. I just read this book, very cute, by Jake Oliver, asking about different things which apparently may not have anything in common, but they do. You are supposed to guess WHAT is it that they have in common. For example: what do the "coquille St. Jacques", the "limace" and the "Poisson-clown" have in common?
They are all  Hermaphrodites. Some are simultaneous hermaphrodites, while others are sequentials. The simultaneous have both sexes all their lives and use them according to who's their partner. The sequential hermaphrodites, like the "poisson-clown", are born with one sex that can change according to the needs of the group.
It is nature. It is their nature.