Dragon's Teeth were anti-tank fortifications that were used extensively during World War II. The obstacles were shaped like large square pyramids and were from reinforced concrete and re-bar. Although they did not immobilize tanks or other vehicles very often, they could prove a hindrance to the overall momentum of progress.
The Dragon's Teeth were designed to immobilize tanks by lifting their treads off the ground from below, effectively disabling them.
They could also redirect the flow of enemy traffic so that it naturally flows into a planned ambush area. The average Dragon's Tooth was about 1.2 meters tall and were often used in conjunction with other fortifications such as Hedgehogs. In combat, Dragon's Teeth proved to be unsatisfactory and were easily destroyed or removed by army engineers. Still, if deployed in the right quantities, (thousands for example) they could stall enemy forces for quite sometime.
Dragon's Teeth were not developed by just one country, but were used more by some countries than others. France used large numbers of Dragon's Teeth in the construction of the Maginot Line. Many Dragon's Teeth were deployed by the British in preparation for a German invasion and, likewise, German forces placed Dragon's Teeth rows in the Atlantic Wall.