My ORA clowns started out in my tank hosting my mag-float... they'd freak out every time I tried to scrape the glass.
They moved onto a powerhead, then a goniopora, then a pink tree, and finally settled into the BTA I bought for them (I had to remove the tree to get them to move).
I think it's only ORA tank-raised clowns that exhibit this type of behavior, which kinda shows that hosting is part instinct, and part learned behavior... they know what they're supposed to do, but they're confused as to what they're supposed to do it with.