Upside down jellyfish - sand vs marbles?

[puddlesplash26]

Hello, I'm not sure if this is the place I should be asking this, but I recently took a visit to my local aquarium and noticed the upside down jellies on marbles. I'll try to attach a picture..(this is my first time posting here so I'm still trying to figure out how to use it). I guess my question would be is, is this humane? My original thought was, aren't upside down jellies supposed to be on sand?
I would love to hear what everyone thinks.
Thanks!

 

[Lowstorm]

I suppose they can't tear themselves on marbles. Which is good, all in all. I don't think jelly fish care, so long as their water is good, they don't get torn mantles (Is it mantle?) and get fed.

 

[saltyfilmfolks]

I suppose they can't tear themselves on marbles. Which is good, all in all. I don't think jelly fish care, so long as their water is good, they don't get torn mantles (Is it mantle?) and get fed.

Yup.
I used the same in a jelly tank as well.