From BRS:
No Aeration, Heat, or Tubing Required!
Brine Shrimp Direct's Brine Shrimp Hatchery Dish is probably the easiest to use hatchery on the market today. The unique design keeps all the unhatched eggs and shells in the outer ring, while the hatched shrimp will seek out the light and swim to the open center section, making harvesting easy, fast, and clean. The shallow dish allows for natural separation where the inner ring keeps the unwanted eggs and shells from making their way to the center. In most cases, it will only take 24 hours for the brine shrimp to hatch, at which point they can be fed directly to your aquarium or placed in another vessel for gut-loading with spirulina or paracoccus powders.