Not sure this qualifies as a still life.
If true, the same could be said of many of the photos in this thread.
Looking at several on-line dictionaries, I see the definition of "still life" includes terms like:
"...inanimate objects..."
"...inanimate subject matter..."
"...all kinds of man-made or natural objects..."
"...an arrangement of objects that do not move..."
By these simple definitions (maybe oversimplified?), the fuel filler cap photo would qualify. Any photos of flowers which are still living should be excluded, while cut flowers are fair subjects. But hey, it's the internet, where every thread can wander off in unexpected (and uncontrolled) directions. One must develop a certain amount tolerance for confusion, ignorance, and anarchy arising from different educational and cultural backgrounds.
In addition to inanimate subject matter, it is not clear to me how much control by the photographer is implied / required to meet the definition of a still life. Is it a still life if the photographer finds the objects already arranged - or is control of the arrangement and lighting by the photographer required? To me, even if found in situ, and the arrangement is untouched by the photographer, the photographer still exercises considerable artistic control over the composition by carefully choosing the camera angle, framing the boundaries, and choosing an exposure which emphasizes highlights and/or shadows as compositional elements.
I often tag many of my photos as "Still-life" even when they are not still lifes in the more traditional style (objects arranged by the artist on a table top). I do this simply because I don't know what else to call them. I do wish we had another commonly used term for photos of objects which are: found in situ rather than arranged, composed by choosing a camera angle rather than by moving the objects, and framed larger than a traditional still life, but smaller than a landscape. My post
#71 is an example of the kind of photo I am thinking of, as are many others in this thread.
Unless/until we can come with another term for this category of objects-which-are-found-prearranged, I am all for a very generous and accepting definition of the still life genre.