This is a frozen mukluk. Mukluks are like boots that we wear on our feet. They are the traditional footwear of many First Nations people in Canada. Mukluks provide great protection from the cold and snow. Our feet stay nice and warm inside mukluks. Sometimes we step in slush, and it instantly freezes on the outside of your mukluks. Mukluks are great footwear for dogsledding.
Clue #1 This stuff is definitely frozen.
Clue #2 Frozen outside but warm inside.
Clue #3 Think feet.