Something of this sort. Was at Target the other day and picked up a few similiar to these for 1$ each. My first thought was to use as others use flat mesh to hold down mosses.
These aren't the same ones I have, just wondering how safe would it be in a shrimp tank? Unsure of what material it's made of since I tossed the tags but if I knew what to avoid I'll remember that when I go pick up a few more.
Another thing was the painted ones have some really easy to remove paint, but rather like the color of the black. So would using paint lacquer then repainting be safer? I have Krylon Basic Black, read multiple times that it's safe for inside aquarium after few days of leaving it dry and seal. Unsure how shrimp would take it though.