[Delphinus]

Razor blade along the glass and as much care as possible. If you cut the byssal gland or if it gets pulled out, the clam gets a poor chance of surviving.

I always keep my clams on rock and let them attach. Usually I have to build a fence of rubble around them, and epoxy the fence to keep them from toppling over. Eventually they usually attach. It doesn't have to be a huge fence, even a small lip so that it sits in a depression, is enough. Or in one case I mounted SPS frags around and let them become a natural fence. I figure eventually I might have to relocate the SPS (or the clam, or both) but for now it makes for a pretty natural looking display and I'm liking that a lot.

The other option is place rubble or a clam shell under them and let them attach to that. Only problem with attaching to rubble is that if you want to move the clam later then you have this rubble to deal with and usually they end up letting go because it's not comfortable in the new position with it. So that's why I usually pick where I want them from the get-go and and do my best to work the surroundings to make it so that they don't fall off.

Crocea and maxima clams really belong on the rock. More often than not they end up in the sand more out of convenience ("it kept falling off the rock") or because it's easier to view them that way. Derasa, squamosa, gigas, and hippopus all have really small or narrow byssal openings so they can do OK in the sand long term but maxima and crocea have these HUGE openings that can be an easy way in for a predator or pest that can irritate them and cause them to lose health. I try to mount all mine in rock now using the fence idea and then making the fence look interesting becomes the fun challenge.

Hope this helps!