This Selaginella only stands about 4-5″ tall and will make a carpet over the vivarium floor.   I’ve had the best luck growing in clay, although it does survive in sphagnum and soil it has never thrived in these mediums for me. The stem is red, and depending on conditions the foliage can be reddish-brown to bright green (as shown here).   It does not mind its feet wet.

Available plants are well rooted in 2″ pots.  They will be shipped potted.  The last photo is representative of the size plant you will receive.