It looks a lot like something called pearl weed, which is I think closely related to monte carlo. The scientific name for monte carlo is micracrathemum tweediei, but if you look up micranthemum micranthemoides or pearl weed, your plant comes up.
Very pretty plant, but if you're looking for a carpeting effect, I don't think it would work for you.
I got monte carlo seeds from amazon actually, which turned out to work great. I planted them in an ice cube tray to use for the dry start method and then transplanted them into the display tank when they were grown out enough to root nicely.