[brizzo]

I've always got them to detach from a rock using a tooth pick, they don't hold on like other softies.

Then use like a peanut butter jar lid, put some rubble/course sand in it, throw in ric, put some mesh (i used an old net) over it to stop it from floating away (not touching the ric). Give it a week or two to attach to the rubble

Now glue said piece where you would like it