Well I have a nutty betta. In my Nano, I habe a pc of cholla that has a root, looks like a little tree stump about 5" diameter at the base. He hang out in it like the Kebbler elf. Lately, I keep finding little piles of MTS around the larger holes. I think he's rolling around in there like a little pig in a wallow.
But, it is his nano. The plants look good, he looks good...I can live with a little dirt on the sand cap.