what is on my acro?

[maxheadroom]

I just got a new Walt Smith acro and it has something living in/inside of it. Does anyone know what it is? It also has a tiny acro crab but I'm not too worried about that. Click the pic for the video

 

[twon8]

Barnacle. Harmless filter feeder

 

[maxheadroom]

Great! Thanks! The coral has encrusted over most of it already