* Stones are generally solid: Most rocks and minerals are solid materials. Their volume changes relatively little with temperature, though some may expand or contract slightly.
* Spongy expansion: The way a sponge expands is by absorbing liquid and expanding its structure. Stones don't absorb liquid in this way.
What you might be thinking of:
* Clay: When clay is heated, it undergoes a process called "firing" which causes it to solidify and harden. This is not expansion like a sponge, but rather a chemical change that alters the clay's structure.
* Volcanic rocks: Some volcanic rocks like pumice are very porous and light, appearing spongy. However, this porosity is due to trapped gas bubbles formed during the eruption, not a result of heat expansion.
Let me know if you have more details about the type of stone or the specific effect you're thinking of, and I might be able to help you further!
