I CALLED THEM SLIME NUGGETS, though I should have been more gracious, as they were one of the few things keeping me alive. I discovered the mollusks on my second day stranded on a desert island called Pargo, in Panama's Gulf of Chiriquí. I carried little more than a knife, a dive mask, and the clothes on my back and hadn't yet taken down a mastodon, so I embraced the variety they offered my coconut-and-termite diet.

Commonly known as limpets, the slime nuggets lived in the intertidal zone. They'd be better cooked, certainly, but I'd been unable to make fire and was lucky to find something I could eat raw. They tasted like soft rubber slathered in gelatin—it took 60 solid seconds to chew each quarter-size chunk of flesh into an ingestible pulp—but their consistency allowed me to savor the fact that I wouldn't die of starvation anytime soon. My brain successfully spun each disgusting bite into a victory until my fifth day on Pargo, when my body finally revolted.

It started with the scum sack, the thin mucous membrane holding in the slime nugget's viscera (also known as guts and shit). Before I could eat a slime nugget, I had to pry it out of its shell and cut out the scum sack. I had grown accustomed to the rainbow of repugnance that erupted, but after three days of choking down the mollusks I discovered that, in all probability, I'd been eating something else, too. With a handful of nuggets in my mouth, and another handful waiting to be cleaned, I watched a phalanx of small, brown flatworms emerge from one of the scum sacks. They had a Hydra-like response to being cut in half: Two heads are better than one. I puked.

My entire caloric intake for the day lay partially digested at my feet, and there was just one way to replace it. I threw the worm-infested mollusk away, sat down defeated, and began cleaning another round.

Before I arrived on Pargo, I'd joked that I, a novice in wilderness survival, was stranding myself because I wanted to update the adage "Will work for food" to "Will starve for work." As fresh slime mixed with the puke's acidic residue, I remembered the joke. "Who's laughing now?" I cursed.

Still, I was confident. One friend predicted I'd last only four days on the island, but I figured on somewhere between 12 and a month. Forty had a nice biblical ring to it. I'd be Tarzan in no time. How hard could it be?