Staryu apparently communicates with the stars in the night sky by flashing the red core at the center of its body. If parts of its body are torn, this Pokémon simply regenerates the missing pieces and limbs. It appears in large numbers by seashores. At night, its central core flashes with a red light. Even if its body is torn, it can regenerate as long as the glowing central core remains intact.
Pokédex entry #120
staryu in Pokémon GO
It's possible to hatch staryu from an egg?
Yes, staryu it's a Pokémon that can be hatched from an egg. staryu can be hatched from a 5km egg.
How many CP would staryu have after evolving?
If you’ve catched a staryu and you want to know how many points it would have after evolving, use this evolution calculator and find out easily. You just need to write your Bulbasaur CP and then click “Evolve”.