Based on the leaf type....looks to be a member of the succulent family of plants, but I’m not sure of the exact species. Do you know? Are you planning on feeding, or just want to place this plant in the enclosure? @Iochroma might know....
A Peperomia, perhaps ferryae, or one of its hybrids. It needs more light than it has been receiving.
The genus does not have any dangerously toxic members as scar as i can tell.