Very realistic foam rock that attaches to glass walls with strong magnets. May be used underwater, or in a terrarium, vivarium, paludarium. This is museum, public display quality. No glue, adhesive or velcro. An easy way to create rock shelves and terraces. Live plants and moss attach easily. Move, re arrange at will. This planter has a 4" diameter hole to hold any size pot up to 4". The hole could also be filled with a substrate material without a pot.