For more than a decade, a vial of rare snake venom refused to give up its secret formula for lethality; its toxins had no effect on the proteins that most venoms target.

It comes from a reclusive redtail coral snake, or Micrurus mipartitus, which is primarily found in Costa Rica and parts of South America.

But recently, an international team of researchers figured out the venom's recipe—a toxin that permanently activates a crucial type of nerve cell protein, causing deadly seizures in prey. The details were published online in the Proceedings of the National Academy of Sciences on Monday.