Instant Sea Monkeys
Sea monkeys (shrimp brine) eggs hibernate without water but add water and they come to life - in their hundreds. This carded pack contains food and feeding, but you supply your container (a clear plastic bowl will do. Don't overfeed, but do feed every few weeks. They grow and after 12 months can reproduce.
But there's a dark secret - they eat each other. Survival of the fittest (greediest).