It is hard to tell from the photo without something in the photograph to give it some scale like a pencil, coin, etc. That said, the leaves look a little large and aren't shaped like the H.c. 'Cuba' I grow.
H.c. 'Cuba' grows more slowly than Micranthemum tweediei (previously M. umbrosum 'Monte Carlo'). Last spring I was growing some 'extras' of both species for our local aquarium club. They were both planted at the same time here is what they looked like.
H.c. 'Cuba' and M.u. 'Monte Carlo' planted 2/15/15
This what they looked like on 3/24/15 (sorry a little blurry)