This looks like one of the Peperomias, possibly P. obtusifolia. This entire genus does well in vivariums.
Here's one of the smaller leaved species, P. campylotropa.

-----
Patty
Pahsimeroi, Idaho
Dendrobates: auratus blue, auratus Ancon Hill, tinctorius azureus, leucomelas. Phyllobates: vittatus, terribilis, lugubris. Epipedobates: anthonyi tricolor pasaje. Ranitomeya fantastica, imitator, reticulata. Adelphobates castaneoticus, galactonotus. Oophagia pumilio Bastimentos. (updated systematic nomenclature)

