Bird's eye

I'm in the process of improving what I've written on microscopes.  In fact, I'd wondered if the microscope contained a lens of an animal eye and when turning the microscope upside down to look into the apertures, or objective lenses, at the bottom, I saw what looked like the iris of a pigeon (in my view, if true, the pigeons in the garden will know everything that pigeon ever did before it ended up in the microscope) at the edge of the aperture - ie, it is the right size and colour.  The other apertures are smaller and I haven't yet worked out from rotating the apertures whether or not it is the same or different images one sees, but I think that probably only one of the lenses contains an eye and that light may enter through other lenses.   I don't think there is sufficient light to view what's on the slide, unless it is within the slide (as I can see from one of my slides, which has resembling images, one in a small second slide and one within the slide, apparently obscured by the label).