The opening in Earth's crust through which volcanic materials pass to the surface is called a vent.

Here's a breakdown:

* Vent: This is the actual opening, often a narrow channel or conduit, connecting a magma chamber beneath the surface to the Earth's exterior.

* Volcanic cone: This is the structure formed around the vent by the accumulation of volcanic materials like lava, ash, and rocks.

* Crater: This is a bowl-shaped depression at the summit of a volcano, formed by the ejection of volcanic materials.

So, while a volcano is the whole structure, the vent is the specific passageway for the volcanic materials.