The Earth’s mantle, on which the crust is lying on, is not made of liquid magma. It is not even made of magma. The Earth’s mantle is mostly made of solid rock. The misconception of a liquid mantle arises from expressions like “a subducted tectonic plate sinks into the mantle” or “continental drift”, expressions that implicitly refer to the liquid element.
The Earth’s mantle is mostly solid from the liquid outer core to the crust, but it can creep on the long-term, which surely strengthens the misconception of a liquid mantle.
Courtesy of the U.S. Geological Society.