white spots on coraline? and something else

[Marcellina]

I have a LR that looks like a branch. It has always had coraline on it. This morning I noticed that there is a little section that has white spots on the purple coraline. Its not sand.

Also there is a small yellowish growth of some sort, looks like a little 'stem' or very skinny tube of some sort?

 

[Chiefmcfuz]

The one on the left is a Caribbean worm snail. Harmless filter feeder.

 

[btldreef]

white marks look like and emerald crab or even a hermit was clawing at that rock for some food. i used to get that alot when i had emerald crabs.

 

[Marcellina]

Thanks Chief and btldreef!