From my limited experience they do stick to rocks placed under them. If they attach themselves to the glass, you should be able to cut the attachment threads with a small blade (cut near to glass).
A few polyps of red zoas and green zoas on a small piece of rock to give away. Note that color is not good as they have been under less than ideal lighting for some time. Preferably can collect in Punggol between 5-7 pm today. Thanks!
So far mine is relatively healthy in a 3 footer. Still not eating pellets but takes a little frozen mysis, which it just decided to try after a month. Been keeping it for 4 months.