Thanks for all the great ideas! Just to clarify... my aquarium is quite large. It's hexagonal and measures 12 inches on each side and 24 inches tall. So regarding plants, I'd prefer bigger sized specimens for this terrarium. I have other smaller containers I can use for the miniature plants some of you have recommended. The aquarium lid has a fluorescent light and various holes to accommodate filters, heaters, and other standard aquarium paraphernalia. So it's not fully sealed. Dennis in Ohio where it started snowing again