How does this
develop into this
Metamorphosis, you say?
The larva of Luidia sarsi is a semi-transparent diaphanous sprite that feeds on algae and grows to a remarkable 4 centimetres.
Then something extraordinary happens.
Instead of changing shape to become an adult, a cluster of cells lining the larva’s internal cavity grows, like an alien invader, and out of these a starfish is born. Floating free from its other self, the adult form settles on the ocean floor, where it survives and grows by hunting down other starfish in the dark of night. Meanwhile, the larva continues its vegetarian existence, grazing the surface waters above.
See also this article on sea squirts as ‘real chimeras’ living in the oceans.