This is on the fifth island, Mud Bog Island. After turning the Fossil over to Bolo, go back to Mud Bog and follow the linear path to the Village of Lost Souls. Explore this place to get the three coins, then return to the main hub to play the gamers. Win three coin tosses in a row to get the Amulet.
Trade the Amulet to the other character here for the Hopeful Flame, then go to the right, take the upper right exit, and follow it around to the fire pit. Use it here and you'll get the Manly Musk.