An old time terrarium classic, Peperomia sp. Banos Ecuador is a charming trailing species whose foliage only reaches about 1/4 inch.  It has a pretty reddish-pink stem (color varies depending on conditions) and the foliage has green venation with pale red between the leaf veins.  It can be slow to acclimate but is a quick grower when established, and will form a mat across a horizontal surface, or drape down in a pendant fashion over a branch.

Available plants are offered as cuttings approximately 10″ long (or two pieces of 5″).  I tried selling these as potted plants for a while but they are challenging to ship due to their delicate and small leaves.  They ship wonderfully as cuttings in sphagnum moss, though!