I like it and I like the piece you knocked off under the rock. Better. You can always add the small piece of stone or other stone pieces to the mossy mound to break up the shape and make it look more rugged, and to balance out the color of the stone better. You can also tint the rock a little darker color and in time algae and perhaps lichens will grow on it anyway. Me, I'd also tuck in some very tiny other kind of plants here or there so it's not just moss. I have a lot of cool lichens like this one around the new cabin in NC that I'll be collecting to add to some of my pots later like these red capped 'British Soldiers' (first photo) Maybe some very tiny creeping thyme (second photo), or some mico mini fern. Lots of mico mini plants (some of them flowering) that you can choose from.
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