Help me ID a leg/arm

[ausmal]

Well, i have to say the corals and fish are great and all that but nothing beats observing your tank at night and noticing after 18 months of the tank up you see new and wonderful things. However, I have no idea what the heck this is! It almost looks like my strombus snails mouth! It's in the rock work, this little arm/tentacle/thing came out, retracts slowly when light shun on it, this is the best photo I could get.. any ideas!? It's about the size of the end of a chopstick.

It's about twice as long as in this photo this is it retracting.

Thanks in advance!

 

[DaJMasta]

Peanut worm? If you see a shell and some eyes it could be a conch mouth too.

 

[penfold2]

Looks like it could be a peanut worm. They're harmless detrivores that commonly show up on live rock.

 

[rayadog]

I agree with peanut. You don’t often see the whole body like that.

*sorry: forgot to ID as requested. Not an arm or a leg

 

[Gumbies R Us]

@ISpeakForTheSeas

 

[EnterName]

I second peanut worm. We recently had one with a very similar pattern here and I explained how they retract. If you see the same process of "retracting into itself", you can be more or less certain it's a peanut worm:
https://www.reef2reef.com/posts/14478829/