T is for Thread

I was wondering what to blip today and I thought why not see what the challenge for the month is:
8. Something beginning with 'T': Take a photo of something today starting with the letter 'T'.
Fat lot of help that is, thought I.
While out I walked by a sluice gate. Lightbulb moment.
This is a male thread - a helical ridge on a cylindrical bar, rod, shank, etc. A female thread would be a helical groove in a cylindrical hole. No smirking at the back please.
I chose this because I like the dead leaf stuck in the grease. Of course I could have just called it Twist.