Hole on monti

[lickyricky]

Hey guys,

Noticed this small hole on one of my corals. When I got near it I thought I saw something draw back into it. Have tons of little tubes (snails?) and was thinking this one made its way INTO the coral?
Any help is appreciated

 

[reef lover]

Could be a vermetid snails, tube worm, coral barnacle, gall crab....