Abstract: Several challenging problems in the animation of deformable objects can be solved by combining existing models with implicit surfaces. The latter are used as an extra layer which coats any kind of structure that moves and deforms over time. Implicit surfaces detect collisions, model local deformations, and transmit response forces to the inner structures. They also control the variations of the object's volume. We present several applications from the animation of organic shapes to the simulation of soft inelastic substances that can separate into smaller pieces or fuse into larger ones.