Well,
The first thing I would do,Is double check just to make sure its not a feather duster.
Go a head and add a pepperment or 2,Wont hurt anything as long as your tanks cycled.The if your hitch hiker turns out to be aiptasia and the pepperments dont eat it.Get some kalkwassier powder and make a paste out it,then smear the paste over the aiptasia.