The little white flecks in the soil for the hibiscus is perlite. Make sure the tortoise doesn't ever have access to that. They will eat it and it can kill them if they eat enough of it. Also be aware that any plant like that grown at a nursery will be grown with systemic pesticides. These pesticides are absorbed into the plant's tissues through the roots and it can take a year for them to dissipate. After a year, I only feed the new growth from plants like these.
Congrats on the new seeds!
It contains asbestos, which is glass.
In the past, I believe some types of vermiculite did contain asbestos. The stuff I see on the shelves now, at least here in CA, specifically says "Asbestos Free" right on the bag.I don't know enough about chemistry to argue...but is this right?
Edit: I stand corrected