Re: [IWAGUMI] Project Scree
My recommendation would be Spiky moss, from my experience it's growth suits iwagumi planting more than any other moss because the growth pattern is much more vertical and rugged and looks more indicative of shrubbery/rough ground.
Marks first Iwagumi, the name escapes me, but that used it very well, also, if you look carefully a lot of amanos tanks use moss in iwagumi's, especially the more "wild" ones.