Sweeper tentacle or something else?

[spectral_ranger]

Is this a sweeper tentacle on this chalice? Pic taken this morning not long after lights starting to ramp up. Haven’t paid close attention but it could be out mid-day too. Nothing around it at this point so I’m not too concerned, but curious.

 

[LoveTheReef]

Looks more like slime and that coral is actually a montipora, possibly undata