A paralarva is a baby octopus that has just hatched from its egg. It's very tiny, about the size of a grain of rice, but it's already starting to look like an octopus!
When an octopus lays eggs, she lays a whole bunch of them at once. The eggs are laid in a special place, like a little nest or cave, where the mama octopus can take care of them. Each individual egg has a tiny baby octopus inside, called a paralarva.
When the paralarva hatches, it looks like a little squid with eight arms (tentacles). It's not quite ready to live on its own yet, so it stays close to its nest for a while.
The paralarva eats lots of little plankton and other tiny sea creatures to grow big and strong. As it grows, it starts to look more and more like a full-grown octopus, until it's ready to leave the nest and go explore the big ocean all by itself!