Ghost plant (Graptopetalum paraguayense).
(Also known as mother-of-pearl plant and Sedum weinbergii.)
This is one of those plants I grew up seeing in my mother's and grandmother's gardens-- and that's where I got my start of ghost plant, too-- a big pot full of these tough succulents that look like flowers carved from stone...
I haven't always had the best of luck with it, though it is a very tough, hardy plant. (I guess I've just been a little too neglectful, from time to time. Maybe I haven't cut it back and replanted it, as you need to do every so often when it gets too leggy...)
The fact that it's come back time and again from a rough patch demonstrates how resilient it is.
Around here, it can take the hottest of the summer sun (though partial shade in the afternoon might help preserve their best looks), yet it can also live outdoors through our winters. (I've gotten into the habit of moving it into the garage when I'm shifting around the tender plants, but I've come to wonder if it might be better off left alone. Maybe I'll leave the bigger pots out, next winter.)
It's easily propagated from a leaf broken off the stem-- and they do fall off quite easily when bumped!
This is without doubt the easiest succulent I've grown, so far, and because it reminds me of family gardens from the past, I'm glad to think that I'll probably always have at least one pot of it growing somewhere...