What is formed when magma solidifies within the vent of a volcano?

When magma solidifies within the vent of a volcano, a volcanic plug is formed. This occurs when the magma rises to the surface but does not erupt, becoming trapped and eventually cooling and solidifying in the vent. Over time, as erosion takes place, the surrounding softer material may wear away, leaving the volcanic plug exposed as a prominent geological feature.

In contrast, shield volcanoes are characterized by their broad, gently sloping sides and are formed by the eruption of low-viscosity lava that can flow over long distances. Cinder cones are typically formed from the accumulation of volcanic debris and ash around a vent, creating a steep conical shape. Lava domes consist of viscus lava that piles up around the vent, resulting in a dome-like structure which grows over time but does not solidify within the vent itself.