Casino
I got a new Maxima - put in on a DSB, it fell on it's side. Moved in on the rocks - it jumped off. Put it back on the sand with a rock underneath it still went on it's side. Put it higher on the rocks - it jumped off. Propped it against a rock on the sand - it moved 6" , leaned up against one of my Crocea Clams and hasn't moved for months. They take turns overlapping mantles but both seem happy (both are upright on the DSB). Yes they do move until they find the perfect place. I have two other Croceas who are high on my rocks and are perfectly content. The Crocea that is on the sand with the Maxima jumped off the rocks three times before I learned my lesson - let them find there own space.
Start medium level on the rocks - if they jump, try low level on the rocks - if they jump again, try on the sand with a rock below them - if they move after that - let them go where they want to.
IMHO Joe