熔岩隧道是透明的透明玻璃容器
Lava tunnel which is a clear glass container (usually a cylinder) with transparent and translucent paraffin oil, which is below the bulb. The lamp illuminates and heats the contents of the cylinder, thus there is lava like moving in paraffin oil. The effect is based on the fact that at normal temperatures slightly heavier paraffin oil (and drowning in it), but with little heated, it becomes lighter and floats.