some clam answers:
Crocea, are burrowing clams, they don't live in high rockwork but they do burrow into rockwork. Place a small piece of rubble beneath the foot and wait for it to attach and move it to a nice high place if you like, but remember that clams DO NOT like high water flow, mid to mid-high is goof but high water flow (usually reefers have high flow mid to high in their tanks) disturbs their mantles and will cause pinching in the long haul. Too many tumble from a high perch can and will eventually damage the clam so take your time and use the sand for attachment then placement.
Shrimps: Peppermint and Skunks are not attackers of clams but they are omnivores and are not adverse to cannibalism in a tank if food is scarce. Peppermint shrimps are notorious for going after clams after dark and cleaners are known to nip at the mantles of clams as well. this isn't the norm but definitely not out of the question either.
All clams can be placed on rockwork, Max, Crocea, Squas, Derasa, Hippos. Placement is a visual thing but the key is to make sure that the byssals(foot) is attached to something, i find using small rubble and flat slate rock works best, this will give you the opportunity to move them when you feel like it. Acclimation is the second step, depending on when you purchased your clam, you need to start them on the sandbed and acclimate them slowly towards your lighting. Example:
Week 1 : sandbed
Week 2: rockwork, maybe 4-6 inches higher
Weel 3: 3-5 inches higher
until it gets acclimated.
Good Luck
