Eye Floaters

When I was young, I first noticed that sometimes these transparent, irregular shapes would appear in my field of vision.

This animated GIF illustrates it pretty well:

I had enough sense to figure that they were little pieces of dust or something, floating in my eyeball.

 Mental Floss:

What Causes Eye Floaters?

It turns out this phenomenon is fairly common. They are actually caused by pieces of the vitreous humor, a gel-like substance in the eye, breaking off and causing a shadow on the retina. We perceive these shadows as the "floaters".