While I'm posting about a desert Selaginella, I figured I'd also post a photo of my Selaginella uncinata, aka Peacock Moss or Rainbow Fern.
This is another type of Spikemoss that hails from moist forests, growing in deep shade. I have been keeping this in a dark bathroom that only has one very small window - being darker than any other space I grow in.
I have had other plants suffer greatly in this bathroom. Even my crocodile fern did not seem too pleased with the low light, but this baby is absolutely thriving and has made quite a bit of new growth in the short period I've had her.
Rainbow moss has an incredible adaptation that is extremely rare in the plant kingdom: iridescent leaves. This iridescence gives the fronds it's blue color, which shows anywhere from purple, blue, or teal depending on how the light hits it - it also helps the plant make the most of low-light conditions, refracting light off the iridescent shimmer of it's fronds.
I hope to play around in the future with light levels with this plant. I've seen photos where the fronds take on nearly every color of the rainbow (hence it's name) with the addition of red and orange tones. Most people claim it has its best color in full shade, which brings out the blue, but I'm unsure how to get the additional colors to show up - my guess is more light but most people suggest this will bring out more vibrant green.
Luckily this plant is one that is very easy to propagate as it grows aerial roots due to being a creeper in the wild. It also can tolerate a wide variety of conditions from partial to full shade, low and high humidity, and to my understanding even fully submerged in water. The cherry topper...? They're also hardy down to zone 6, which is an absolute rarity for this family with most varieties being frost tender.