Starfish, which are also sometimes called sea stars, are much better at healing themselves than people are! If they lose one of their rays (which are their arms) they can grow it back!
Starfish don’t have a lot of natural defenses, so being able to grow back a ray is really important to helping them survive! If an animal bites off one of the rays, a starfish can escape and heal!
Their bodies automatically know that they should have a certain number of rays, and if one is missing, a new ray will start to grow right where the old one was. A few starfish can even grow entirely new bodies from just a single limb!
People should never try to cut off a starfish’s ray on purpose, just to see it grow back. Starfish need their rays to help them move around, so removing one on purpose wouldn’t be very nice.
A lot of scientists study starfish to try to find a way to help people grow our own limbs back. Until that happens, if a person loses an arm, that’s it there’s no more arm, and a new one won’t grow. Some parts of our bodies, like our hair and our fingernails are always growing, so those are okay to clip. We have to be careful though with the rest of ourselves!