This plant arose as a seedling from my packet of rosularia sempervivum - I got plants that are likely the correct species, too. The interloper grew much more quickly than the rosularias, so I gave it is own little trough, and now I'm curious what it is. For a sense of size: the planting area in the photo here is about 2 inches wide. Growth is floppy and soft. What is my happy bonus plant?
Do you happen to be on Facebook? There is a forum there where a few succulents experts hang out. If not, I could post your photo there if you like to see if they can ID it.