The rest of the story: KLH is too big and comoolicated to synthesize, so giant keyhole limpets still offer the best, most stable supply of the portein. Before extraction, Stellar employees move the limpets to tanks indoors. Researchers use a syringe to extract the limpet's blood and then isolate KLH using a centrifuge. It takes about 16 weeks before the mollusk has fully recuperated and is ready for its next extraction. Limpets can also be harvested in the wild, but they die during the extraction process. There aren't enough limpets in the sea to keep up this method. More than a dozen vaccines that useKLH are in clinical trials, and a treatment for bladder cancer is now approved for use in Europe and Asia. Stellar currently makes between one and two kilograms of KLH a year. But if a KLH cancer vaccine is FDA-approved, Oakes says it "will icrease demand by orders of magnitude"