Glass Flower Vases

I speak regularly in clear glass vases.

Yes, generally PVC, unfinished Terra Cotta, and the glass is perfectly safe to use in your tank.

I use square or triangular candleholders and silicone gravel for them. Let stand for 48 hours to fully define and use them but the caves of my bettas.

Yes, I know they are used for food.

The safest thing to do is use things for aquariums