The Internet's a funny thing -- or a funny place, or whatever it is -- where the most basic assumptions are, quite often, turned neatly inside out. For example: Most people might reasonably suppose that a huge amount of information about a 12-year-old girl once celebrated as the "world's strongest seventh-grader" must surely exist all over the Web. Right?
But LIFE.com's rigorous research (and by "rigorous" we of course mean that we queried both Google and DuckDuckGo) failed to find anything but the most cursory details about April Atkins -- a cute, perpetually grinning pre-teen who, for one brief, bonkers moment in the mid-1950s, routinely blew minds at California's famed Muscle Beach by performing utterly improbable feats of strength.
In fact, it seems that there's very little information out there about this extraordinary human being.
The photographs in this gallery, for example, made in 1954 by LIFE's Loomis Dean, never even ran in the magazine. But as the video below suggests -- and as Dean's wonderful, lively pictures attest -- there was a time back in the day when 79-pound April Atkins of Pacific Palisades, Calif., most definitely had her moment in the sand and the sun.
[That's Dean, there to the right, balancing Atkins on his shoulders at the original Muscle Beach near the Santa Monica Pier. Today's Muscle Beach -- located just a couple of miles south of the original -- is, strictly speaking, "Muscle Beach Venice." Why Dean isn't balanced atop April's shoulders is one of those riddles that will, evidently, forever remain cloaked in mystery. You can see the charming photo at full size by clicking on the image.]
Besides wondering what became of her later in life, we really have just one question about all of this: How the hell did little April Atkins manage to do what she did?
Finally, here's a video of April in action. Brace yourselves: There's stuff happening here that will make your hair stand on end. In a good way.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter @lizabethronk.