What Are Sea Monkeys? Lol?

I'm kinda just browsing around and I got bored, and I have a WHOLE LOT of sea monkeys. if you don't know what they are look at google images. they come with a little home for them, eggs, and this weird green powdery food, i think its like algae or something. well anyways, they kinda look like shrimp. There's ALOT of them growing in the home that i have for them. they started hatching about 5 days after I put the eggs in. I'm just wondering... what are they? and how do they grow?