The theme that structure determines function is one of the most significant cornerstones in understanding natural sciences. On the other hand, recently revised science curriculum in Turkey has emphasized science and engineering practices to help students be able to converge science with the other disciplines by applying theory into practice and product; but there is not an emphasis on the repeating patterns and relationships between structure and function for natural and built systems at any grades. In order to close this gap, the main objective of this study is to develop an integrated biomimicry STEM activity about the unit of Living Things World at grade five. This paper reported on a case study of 21 fifth-grade students" gaining experiences about the engineering design process by mimicking a structure from the organisms to solve a human problem. Even more striking result is that students can manage to incorporate biomimicry into their design solutions by the way of complementary relationship between structure and function in organisms.