Tesserae terrain on Venus, which was first detected by the Soviet Venera 15 and 16 spacecraft in the early 1980s, is characterised by complex intersecting ridges and grooves. This terrain may have been formed by large blocks of material sliding and collapsing down slopes, pulled by the force of gravity. In the extremely high-temperature Venus environment, rock can behave more like a fluid, unlike the rigid behaviour of rocks found on Earth.