Today is National Sea Monkey Day.

Marketed for the first five years under “Instant Life,” the phenomenon has continued to thrive half a century after its introduction to millions of delighted children around the world.

Today’s Sea-Monkeys are the hardiest generation of Artemia NYOS, a hybridized form of brine shrimp, tiny crustaceans of the animal family shared with lobsters and crabs. NYOS stands for the New York Oceanic Society, the Long Island laboratory where Harold von Braunhut, mail-order marketer and inventor, created the species.

Unborn Sea-Monkeys undergo cryptobiosis — literally, “hidden life” — by remaining in suspended animation inside the egg awaiting proper hydration to spring to life.

In 1957 von Braunhut introduced his product to compete with the ant farm popularized the year before. Chain stores initially refused to carry von Braunhut’s product because of a recent disastrous rollout of Wham-O’s “Instant Fish” toy, so he marketed “Instant Life” directly to children through comic books, purchasing about 3.2 million pages of advertising each year. He changed the name to “Sea-Monkeys” in 1962.

Many are well familiar with the process of growing Sea Monkeys: Add a packet of “water purifier” to a tank of approximately 12 ounces of water. Wait 24 hours and add the packet labeled “Instant Life Eggs,” and tiny frolicking creatures seem to appear instantly — and miraculously.

That illusion of spontaneous life is, in fact, unveiled with a bit of optical abracadabra. The first packet contains some eggs, which hatch before the second packet, containing additional eggs, is added. That second packet contains a special dye which makes the first hatchlings suddenly visible. Voila! Instant life.

The Sea-Monkey species of brine shrimp is not found in the wild. It was developed over several decades into a breed that can grow up to two inches long and live for years, much larger and longer-lived than their ancestors.

The originally marketed species was so comparatively fragile — most of the shrimp lived about a month — that each kit included a “Sea-Monkey life insurance policy” good for two years after purchase.

The hardy little adventurers have been in space. In 1998 John Glenn took 400 million sea monkey eggs on a nine-day shuttle mission. They were hatched eight weeks later with no apparent ill effects.

The popular critters have been featured on television shows such as Night Court, Spin City, Roseanne, Third Rock from the Sun, It’s Garry Shandling’s Show, Desperate Housewives, American Dad, The Simpsons and South Park.

Test your knowledge with some fill-in-the-blank trivia questions about the world’s most famous living toys:

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