Johnny, they are the little ecosystems that run themselves - kind of like a snow globe, except you don't shake it . I'm trying to remember the name of the shrimp. I think Curt has one of these. I'll do a little digging and see what I can come up with.
OK...I was trying to rack my brain because I remembered seeing these at Inland Aquatics. Then it dawned on me....I believe they are Volcanic Shrimp or Halocaridna rubra