I think Mom let me order the sea monkeys when I was about 8. I got a few to hatch. It was a big disappointment.
In high school, I took up guppy breeding. I used to raise brine shrimp by the thousands in a gallon pickle jar. As I remember, I had a 60 Watt bulb trained on the jar the shrimp would gravitate towards the light and I'd suck them up with a turkey baster. The guppies fed ravenously on them.
I grew some brine shrimp when I was a kid. Even enjoyed looking at them through my microscope. I now live where they come from - right near the Great Salt Lake. Collecting brine shrimp eggs is a multi-million dollar business here, done in the winter. It's brutally cold out there skimming the floating eggs from the surface, and the boats don't last long in that extremely salty water. They work with spotter planes that find rafts of floating eggs - they look like reddish algae - and direct the boats to them. There's hot competition among the several companies and boats to get the most the quickest.
The eggs are shipped by the ton to Asia as food for fish farms. Minus the pound or three sold as sea monkeys.
I filled out the order form and put some change in an envelope. My mom said she would mail it but since I never got the SeaMonkeys I assume she never mailed the envelope nor ever intended to. My attention span was about 5 minute back then and I’m sure I forgot about the whole affair by lunch that same day.