Yep yep...
my LFS guy told me to not actually submerge those bananas more than about
1cm. I also read that you can just pop it there, and it will soon root
itself in.

Mine has HUGE roots going along under the sand. and one or two new tubors
also, which remain above sand.

I saw one of these plants in a shops personal aquarium, and it was even
bigger...really lovely.