A UCLA study has found that a common strain of Caenorhabditis elegans—a type of roundworm frequently used in laboratory research on neural development—has a pair of genes that encode both a poison and its antidote. The new research also revealed that if worms with the two genes mate with wild strains of C. elegans that don’t have both genes, their offspring who don’t inherit the antidote can’t protect themselves from the toxin—which is produced by mother worms—and die while they are still embryos.