Yep. Spongy. Then after you slice you coat with kosher or sea or rock salt, press under paper towels like set a dish or pot on them for 10 minutes, or let sit for a good 2-3 hours without weight (the salt and pressure remove the majority of the moisture, so they don't get all soggy & it help removes the bitter taste. The salt will do it on it's own, but it takes awhile).
Buh-bye rotting mushrooms!