Biologists have re-shaped the body design of snails. Exposure to platinum results in the formation of an internal shell instead of the normal external shell. During embryogenesis of the freshwater snail a time slot of just one or two days determines whether the animals form an outer shell or not. Reprogramming of the direction of growth of the molluscs´ shell-generating tissue during this sensitive phase prevents the development of the usual convoluted shell. In lieu thereof a small hollow cone grows inside the body — similar to whats happens in squids.