1. Grind cake into fine crumbs; mix with frosting in a bowl to form a sticky dough. With greased hands roll mixture into teardrop shapes, 2 inches long. Insert licorice into rounded ends. Transfer to a parchment-lined baking sheet and freeze until firm, 25 minutes.
2. Melt chocolate melts. Place cookie crumbs in a pie dish. Dip each rat in melted chocolate, leaving tail uncovered. Coat with cookie crumbs and insert almond "ears"; let chocolate and crumbs set before transferring to parchment. Brush excess crumbs from rat face ad use dabs of melted chocolate to adhere sunflower-seed "eyes". Repeat with remaining rats. Keep chilled for up to 3 days.