The nature of science describes what science is, how it works, and its interactions with society under the perspectives of philosophy, history, sociology, and psychology of science. Understanding it is an essential aspect of scientific literacy. Given the critical role that school textbooks hold, considering what is taught and how it is taught in schools, we find the presence of the nature of science in school science textbooks to be significant. In this research paper, all Greek biology textbooks of lower secondary education are analysed to evaluate whether principal elements of the nature of science can be found in them. The whole array of educational resources available (textbooks, workbooks, lab guides, teachers’ books) was analysed as well as the corresponding official biology curricula. Content analysis was the method of choice, and the ‘meaning unit’ was the unit of analysis. We found that most of the nature of science references in the material that students were taught in 2021/22 was implicit and not especially designed by the curriculum. Some nature of science aspects were more commonly found (e.g., evidence is vital in science) than others (e.g., science has limits). The most opportunities for the nature of science to be introduced were found in history of science vignettes, laboratory activities, and some optional inquiry activities. However, without a structured design from the curriculum, it is the teachers’ responsibility to design and facilitate nature of science instruction (or not). We conclude that lacking explicit references, the nature of science falls into the hidden curriculum and becomes falsely depicted, enforcing a positivist image of science.