that it's possible to grow plants on glass marbles. OK, not literally!
I used it quite a lot in the garden, then i came to the idea to use it a small outdoor garden aquarium with also a few tropical plants, back in 2017. Used it as a base layer sloped up only at the left and right side corners, Nothing in the middle. Then capped it with river sand and capped that again with gravel.
This is the result in the first year.
It still is setup today with the very same soil and each year 2018 and 2019 it grew plants like mad and never fertilized it.
I'm pretty sure Crypts will love it.