Potatoes can absorb and reflect Wi-Fi signals
When Boeing wanted to test out its wireless signal on new planes in 2012, they placed giant piles of potatoes on seats. Because of their high water content and chemical makeup, potatoes absorb and reflect radio and wireless signals just like humans do.

Source: https://www.insider.com/amazing-food-facts-2017-12#potatoes-can-absorb-and-reflect-wi-fi-signals-14