What's the purpose of fighting the Starfish in first level?

[HunterN]

Hey, really loving the game so far! The over world is so sick too and it has fun water movement like Majora's Mask or something. Anyway, I instantly killed the starfish mini-boss but it didn't seem to drop any items or anything unless I just didn't notice picking something up? What was the purpose of it?

Also, the starfish boss (and first world boss) were a bit annoying since they would teleport to the middle of the arena and instantly damage you.. maybe they should not be able to damage when teleporting for a second or so?