The lfs close to here used to have them, so I ended up with a couple. I watched them release eggs and sperm into the water once and I guess some of them managed to grow in my fuge as now I have 5 more crawling around in my sump/fuge. I am not sure how common they are but I do have a few and they are pretty cool lookin though dont see them very often as they mainly come out at night. Cant really see their shell especially when they are small but as they get bigger there is a little white line that runs vertical across their back which is the only part of the shell that you can see.