Some of my Xenia's have moved off the original rock from the LFS-- Most have planted on my LR but some flew off to the bottom of my tank-- How can I get them to plant on a rock? I am about to fish them off the bottom but I can't just sit them on a rock b/c the current will surely blow them off--- I am about to get them out now and just need some quick help so I won't lose these other xenias--