We had a complete exoskeleton perched in a plant a while back. That was a fun one to explain to my 5 year old. Is it dead? Why isn't it red? Is it bones? Where did he go? How does it grow? Can he swim? Is it a ghost?
Aquariums are such a great learning tool. Natural science all the time. I just donated my extra 10g with all the fixin's and 10 baby mystery snails to the kindergarten classroom. Their betta is really digging the upgrade! I should bring them some ghost shrimp or something too.......