It will likely retract into nothing as soon as you touch it. Don't stop! They can shrink into a surprisingly small bit of nothing when in danger. It may be the case that you have others in your tank already.
I did not find the Joe's juice to be a viable solution in a tank that has lots of hard to get to places. A pair of peppermint shrimp cleaned the tank of aptasia in a week or so. The only thing I have lost that was not aptasia so far is a pair of 2mm sized mushrooms.... No free lunch. It's an option.