Put him there and see how he does. If you start to see the mantle lighten, then you know you need to move him higher. Do not super glue him, as stated, clams move/jump when not happy. If he's glued down, this can ultimately irritate the clam to death. If you have a rock that you can put under the clam on the sand bed, do that till he attaches. Once attached, move him where you want :up: