So cute!
My thought as well. Because the seed has germinated so quickly and so well, I would suspect it isn't a carpet plant, have a look at <(Probably not.......)>.It will be interesting to see what they grow into. I've heard mixed reviews about seeds i.e. they are often not what they are sold as. The pictures are often the seed leaves (the first pair of leaves a plant grows) which can be quite different to how they look mature. Looks very nice at the moment though!
That was the eventual identity of the plant in @three-fingers <"(Probably not......"> thread.I've seen an youtube video about them and the Guy said those were hygrophila sp?