If it's a CRS, the same thing is happening to one of mine. It's not moving either. I suspect it could be a lack of minerals or water conditions not suited for them. I do think it is alive though. Yesterday it was under a rock, lat night it was under some driftwood, and this morning it's under some java moss. My ph is slightly high so that might be the cause. The rest of them seem to be doing fine. They're not as active as they used to be, but their colors are normal. The babies are alive too, and are growing. I'm going to add some IAL tonight to lower the ph a bit and see how that goes.