I got some of the littleneck clams Wednesday and all were alive (I went the first day of the sale to maximize my chances of this). I RO/freshwater dipped them for 5 min or so then drained most of that out and dripped tank water on them. They started opening up and excreting pretty soon after that. I left them in there a couple of hours then put 6 in our display tank's fuge, 6 in our stock tank's sump, and a couple in different small quarantine and food culture tanks. So far all are open and seem happy, well, as clams.
The ones in the 'fuge have burrowed down into the DSB and all I can see are their siphons, the others are in barebottom environments.
We'll see how it goes.
-Sonja