Protandry

Protandry is when some animals can change their sex from male to female as they grow up, like how caterpillars turn into butterflies. Think of it like this - some animals start off as a boy, but as they get older, they can change their body to become a girl. This is different from humans or most other animals, who stay the same sex for their whole life. Some fish, mollusks, and even some frogs are examples of animals that can do this. It's just like magic, but it's really just nature doing its thing.