Is it stone? Or foam?

Geneva, Illinois is a well-preserved river town with darling old homes that have plaques, so it came as a surprise when my hand gently rapped against a brick wall and I discovered by its hollow knock it was foam, not brick, but foam. Utterly fake in fact, phony as can be. And it's ubiquitous. Those mansions? Foam. They weigh nothing. Fancy archways, foam festoons, faux Roma, Olive Garden everywhere. Durable, cheap, lightweight, capable of assuming any form, foam could be the answer to affordable housing for seniors. It's fully insulated by nature, quiet and odor-absorbing, plus it's the perfect housing for tornado alleys and earthquake faults.