New tank with a hitchhiker?

[SWstart]

I recently invested in a tank from someone who was moving. The coral was beautiful and everything looked healthy and well. I recently noticed a new small white mass on a rock that was in the tank that was never there before. After some small investigating me and my wife thought that it was a anemone but can’t tell what type due to it being a juvenile. I’m new to the site and to the hobby, I’m hoping I may find a few answers to some questions like, will this grow into something dangerous In my tank? Like a coral, snail, shrimp, or fish killer? The specimen is very small, maybe the side of the end of a pencil eraser? It is beautiful and if undesired will be given to another saltwater enthusiast.

 

[Benjammin]

Bump

 

[SWstart]

I tried to get a few better pictures

 

[SWstart]

Bump in hopes