Czech hedgehog

noun1

1. •
   A static antitank and anti–landing craft obstacle, widely used during World War II, constructed from three mutually perpendicular steel rails connected in the form of a tripod.

   • Omaha Beach was shielded by about 3,700 obstacles, including 450 ramps, 2,000 stakes, 1,050 Czech hedgehogs, and 200 Belgian Gates. These followed a standard pattern. — 2013