Here's why:

* Formation: Pumice is formed from volcanic eruptions. It's created when lava with a lot of dissolved gas cools rapidly. The gas bubbles become trapped, creating the porous structure of pumice.

* Composition: Pumice is typically composed of volcanic glass (silica) and minerals like feldspar and quartz.

* Texture: Pumice has a distinctive frothy, bubbly texture due to the trapped gas.

While pumice can undergo changes over time due to weathering and erosion, its fundamental origin is igneous.