In this paper, we study the optimal deployment pattern problem in wireless sensor networks (WSNs). We propose a new set of patterns, particularly when sensors' communication range ( ) is relatively small compared to their sensing range ( ), and prove their optimality. In this study, we discover an interesting phenomenon-pattern mutation. To the best of our knowledge, this is the first time that mutation in pattern deployments has been discovered. This phenomenon, which contradicts the conjecture presented in a previous work that there exists a universal elemental pattern among optimal pattern deployment, significantly furthers our understanding of optimal patterns in WSNs.