I went with my daughter to the reptile shop to get some isopods and springtails for her gecko tank.
She has had a crested gecko for almost two years. It is a bit of a chore to keep the substrate clean, since the gecko likes a tank packed with plants branches, etc.
Isopods and springtails to the rescue. These guys apparently eat gecko poop and pee, which automatically makes me a big fan. While my daughter bought the critters, I had a good look around the store.
FYI, I can't identify any of these creatures:
Someone recently pointed out to me that besides reptiles, cats also have slitted pupils. Perhaps a relic of the mesozoic era.