You can rubber band them to the rock you want them on. Band them tight enough to keep them on, but not so tight that you cut them in half (unless you want to, that is!). They usually attach themselves by this method after several days. I usually leave mine for about a week or two just to insure they are attached. Sometimes they will still slip out of the bands. If your current is too strong or if you have a power head blowing directly on them, this will make them detach from rocks.