ST. LOUIS COUNTY - St. Louis County Parks and Recreation has announced it recently received a report of an invasive hammerhead worm at Cliff Cave Park in St. Louis County, warning visitors that the flatworm can harm the local ecosystem and pose risks to people and pets.The hammerhead worm, originally from Asia, preys on native earthworms, which are essential for healthy soil. Officials said the worms are usually seen after heavy rains and tend to hide under logs, rocks, and leaf litter.Hammerhea...