Rare Purple Janthina Shells Wash Up on La Jolla Beach After Decade Absence

In a surprising discovery on the shores of La Jolla, California, a rare and vibrant purple shell has washed up, captivating locals and scientists alike. Anya Stajner, a Ph.D. student at UC San Diego’s Scripps Institution of Oceanography, stumbled upon this tiny treasure during a sunset stroll. She immediately recognized it as belonging to a pelagic sea snail known as Janthina—a species not seen on San Diego beaches since 2015.

These marine snails are a marvel of nature, sporting striking purple shells and floating on the ocean’s surface with the help of a natural ‘bubble raft.’ According to experts at Scripps, Janthina are typically found in subtropical and tropical seas, and their rare appearance on Southern California shores is often tied to warmer offshore waters drifting toward the coast. Could this be a sign of shifting ocean patterns?

What makes Janthina even more fascinating is their clever survival tactic called countershading. Their darker top side blends with the ocean surface when viewed from above, hiding them from hungry seabirds, while their lighter underside camouflages them from fish below. It’s a brilliant disguise—nature’s own invisibility cloak. But beware if you pick one up: these snails can release a purple ink that might leave a stubborn stain.

Stajner suspects that a patch of warmer water in the cove is responsible for bringing these elusive creatures to shore, reminiscent of a similar event during the 2015 El Niño and marine heatwave. For locals like Brooks Whitney, the sighting is both awe-inspiring and puzzling. Are these purple shells a fleeting wonder or a hint at deeper environmental changes? Only time—and the tides—will tell.