Sea stars do not have brains or any blood. They filter water to pump nutrients through their nervous system.
They used to be called starfish but since they’re not technically fish, sea stars is a better name. They are echinoderms. Your echinodermis is showing!
They can live for over 30 years.
They are NOT fresh water creatures.
While sea stars can regenerate limbs, it takes many months, even up to a year, to fully regrow them.
They can reproduce asexually from a lost limb or even by releasing sperm and gametes (eggs) into the water. Fertilized gametes fall to the seafloor and develop sea star larvae which end up growing into sea stars.
Some may have over 30 arms
The coolest thing though... look how they eat. They essentially “release” their stomachs and liquefy their meals then suck it back in.