Missing Frog

I woke up to feed my rasboras and say high to my tank friends, but I could not find my frog. He was fine yesterday, hanging out floating and swimming. I looked everywhere and I moved some of my wood pieces and rocks to see if he would swim out, but he never appeared. I looked at my filter cover and I saw a very small piece of what looked like it could be part of my frog. I took it out with tweezers and examined it under my pocket magnifier and it looks like it could be a piece of him. It was squishy, but hard. My tank is well established/cycled and I recently tested it, everything came back within optimal ranges. Could he have died and my fire shrimps and my mystery snail, Gary, have eaten him over night?