Pacman percolation: a model for enzyme gel degradation
  We study a model for the gel degradation by an enzyme, where the gel is schematized as a cubic lattice, and the enzyme as a random walker, that cuts the bonds over which it passes. The model undergoes a (reverse) percolation transition, which for low density of enzymes falls in a universality class different from random percolation. In particular we have measured a gel fraction critical exponent beta=1.0+-0.1, in excellent agreement with experiments made on the real system. 
T. Abete, A. de Candia, D. Lairez, A. Coniglio