Actually, rhizome plants DON'T root in substrate . . . EVER. Also, ALL rhizome plants will have their rhizome rot without proper flow of water over it-- which means the plant will die. That's why I get erked when I see em in/on substrate.
but I was thinking...would it be ok if i tied the two anubias to flat pebbles, then half-buried the pebbles in the sand? Cos I kinda like them where they are...