Czech hedgehog

The Czech hedgehog (Czech: rozsocháč or ježek) is a static anti-tank obstacle defense made of metal angle beams or I-beams (that is, lengths with an L- or 𝐈-shaped cross section). It is similar in shape (and design) to a much larger version of metal knucklebones or caltrops. The hedgehog is very effective in keeping light to medium tanks and vehicles from penetrating a line of defense; it maintains its function even when tipped over by a nearby explosion. Although Czech hedgehogs may provide some scant cover for attacking infantry, infantry forces are generally much less effective against fortified defensive positions than mechanized units. The author of the Czechoslovak invention is Major František Kašík.