Protosemiotics is the study of the rudiments of semiosis, primarily in nature. The extension of the semiotic field from culture to nature is both necessary and possible in the framework of Peirce's semiotic theory. Against this extension, the critique of pansemiotism has been raised. However, Peirce's semiotics is not pansemiotic since it is based on the criterion of thirdness, which is not ubiquitous in nature. The paper examines the criteria of protosemiosis in the domain of physical and mechanical processes.