Lectures prevail as a ubiquitous teaching and learning method across universities worldwide. Whereas lectures have been conceptualized from language-centred perspectives, lectures' materiality as linked to their socio-cultural and historical meanings have been scarcely explored. To address this gap, we tackle the materiality of communication in ten live recorded lectures -- collectively viewed more than 1,000,000 times -- uploaded by 'top-ranked' universities in India, Japan, Russia, Egypt, Palestine, Spain, the USA, the UK, Italy and Canada, on their websites or "YouTube" media channels. The materiality we refer to comprises the key things/artefacts and bodies in the lectures. A multimodal semiotic analysis of non-verbal and material elements of a lecture is applied on the videos to first 'map' its material ingredients, and then explore associated meanings that form socio-material assemblages. The findings point at a few salient thing and body characteristics, such as the monofocal lecture platform, the omnipresent blackboard, the underrepresentation of female lecturers, and the low diversity and use of digital technology. We discuss these via the 'body and thing idioms' (Goffman, "Behavior in Public Places: Notes on the Social Organization of Gatherings." New York: The Free Press, 1963) that mediate lecture hierarchies, historicity, meaning making and engagement, calling for wider acknowledgement of multimodality and socio-materiality in university practices.