Any help ID'ing these critters?

[Holy handgrenade]

Good day to you all! So i bought 2 macro algae pieces "moss balls" from kp aquatics to see if i could get some brittle stars and other cool little crittters. Well i added this algae to a fish breeder box hooked up to the back of my tank and just today moving around some rubble and found this little guy. Any ideas on what he is?

 

[sixty_reefer]

Elysia slug herbivores

 

[Holy handgrenade]

Elysia slug herbivores

Are they harmful? Should i remove it? I was thinking it was some type of slug

 

[sixty_reefer]

I wouldn’t remove it, they a nice addition to the CUC. It is a slug and will help with algae

 

[Holy handgrenade]

Ok thanks man!

 

[Holy handgrenade]

Also what in the world is this @sixty_reefer ? It retracts after disturbing it. Is it some type of worm or something? It has been in the same spot ever since i had the algae

 

[Holy handgrenade]

Sorry for the crappy pictures, i tried my best with my phones camera

 

[sixty_reefer]

Sorry for the crappy pictures, i tried my best with my phones camera

That’s an Aipatasia, cut a large chunk of algae on the area surrounding it and discard of it, keep your eyes for more

 

[Holy handgrenade]

That’s an Aipatasia, cut a large chunk of algae on the area surrounding it and discard of it, keep your eyes for more

Haha! Here i am, all new to the hobby, and looking at aipatasia as a cool and interesting critter