	Sea otter pups display a propensity for manipulating objects between their paws and regularly pound rocks and little bits of coral against their bodies in a random and curious manner. According to some of the earlier otter behavior biologists, Hall and Schaller, this, "tendency to manipulate and pound is far from stereotyped in its application and seems to prove the basis for learning the use of tools in feeding behavior". The first indications of tool use are observed at 5 weeks of age when pups will slap their forepaws against their chest. By ten weeks of age, they attempt consecutive dives with the same rock as they learn to swim.