The conduit that connects a pool of magma to the crater of a volcano is called a volcanic conduit or conduit.

Here's a breakdown of its role:

* Magma Chamber: This is where the molten rock (magma) resides beneath the Earth's surface.

* Volcanic Conduit: This is the vertical or near-vertical channel that acts as a pathway for magma to travel from the magma chamber to the surface.

* Crater: The opening at the top of the volcano through which the magma erupts as lava, ash, and gases.

The conduit plays a crucial role in volcanic eruptions. It channels the immense pressure from the magma chamber, allowing it to reach the surface and erupt. The size and shape of the conduit can influence the style and intensity of an eruption.