Can anyone identify this small red object?

I go with a bottle cap. I don't know if there's a word for the type of photography you describe. I will say that your son at 5 has an uncommonly curious eye.The point of view at which this shot was taken demonstrates study and planning as opposed to the usual "Oh look! [snap]" of most picture takers, and not only children. Encourage him. Take one of his shots that has aesthetic appeal, print it, frame it, and put it up on a wall.

It's the inside part of a bottle cap, looked from above. The blue stains could have come from a blue marker, or paint.

In terms of photographic styles I would say "macro photography" for the first one, and "still life photography" for the second one.

By the way I like the second photo.

That looks like a capped drain pipe. It's probably in your basement or under your house.

I thought it was something bigger, but I figured it out. Here's a size reference photo. If someone gets it, BA.

Pentel pen cap?