Doraemon Chapter 365

Doraemon introduces Nobita to a gadget called the Head of the Gorgon, which can turn living things into stone but people are okay as long as it only petrifies a small part of them. So Nobita used it to petrify his legs to help him stand outside class as punishment without getting tired. However, the gorgon is later let loose and petrified many people in full turning them into full stone statues. In the original manga, the teacher, Doraemon, Suneo and Gian fall victim but the 2005 anime extended the story so that Shizuka is also turned into stone.