If you're ever in South Dakota during a hailstorm, you might want to put on a helmet. On July 23, a record-setting 1.9375-pound hailstone with a circumference of 18.6 inches hit the ground during a powerful storm and brief tornado around rural Vivian, according to the National Oceanic and Atmospheric Administration . The ice ball, which probably shrank "considerably" before it was recovered, beats the previous record holder found in Aurora, Nebraska, in 2003, and another that fell in Coffeyville, Kansas, in 1970. "It should also be noted that many other stones with diameters exceeding six inches were also noted during the storm survey!" NOAA boasts.  The Associated Press  reports that the largest hailstone ever in the United States may also be its most traveled: The cold stone has been whisked about 370 miles away, to the National Center for Atmospheric Research in Boulder, so that researchers can study it. While the tests planned for the hailstone are unclear, a tweet announcing its arrival warns, "Hey, keep that away from the margarita mix!"