Acropora unidentified pest

[Squirrel309]

Hey legends, long time lurker first time poster, I've started dipping my toes into sps and noticed this little critter on my acro that I can't identify with research, it it has acro flesh over it but little whispy fingers pulse in and out say every second or so, at first guess some kind of barnacle? Any help appreciated

 

[tbrown]

The description sounds like a barnacle but that's pretty small if it is.

Barnacles are typically harmless.