A lava dome is a type of volcanic feature formed by the slow extrusion of viscous lava. Unlike the fluid lava that creates broad, shield volcanoes, the lava in a dome is thick and sticky, causing it to pile up near the vent. This results in a steep, mound-like structure that can grow over time as more lava is emitted. Lava domes can vary in size and shape, often appearing as irregular hills. They are typically found in volcanic regions, such as those associated with stratovolcanoes like Mount St. Helens or Mount Merapi. As they grow, they can become unstable and may collapse or produce pyroclastic flows.