Terry clips (named after the original manufacturer, Herbert Terry, who were also the original manufacturer of the Anglepoise lamp).With further investigation, could it be a tool clip? This one is from the UK which would make sense given production locations:
https://www.amazon.co.uk/TOOL-STORAGE-SPRING-TERRY-CLIPS/dp/B0070PSMYO
View attachment 799059
They are also available with plastic coating if you are worried about damaging the engine cylinder.