EN
The four dimensional view of material objects and the idea of temporal parts are considered as two sides of the same coin known as worm theory. As it is argued, objects extended in space have spatial parts while temporally extended objects have temporal parts. The aim of the paper is to show that the notion of temporal part is frame relative and that its role in the ontology of four dimensional objects is often overestimated and misconceived by the defenders of four-dimensionalism.