Whats this on my rock

[Samba]

Hi, just started my first tank and it's on cycle, noticed this red thing on my rock I bought, is it a worm? If so anyone know what kind?

 

[Convict2161]

Looks like Aiptasia

http://www.reefs.org/library/aquarium_net/faqs/aiptasia.html

If you poke it does it dart back into the rock?

 

[Samba]

Yes it does, just poked it and did jump back into it's hole, it also closes up when the light goes off, thanks for the link, it doesn't sound good for when im ready to start adding corals

 

[Madcrazyroyboy]

Use red sea aptasia x.