This one isn't exactly a "bump" but I thought it would be good to include in my series (see these posts on eye and eyelid bumps).  Every once in a while,  I will have a concerned child or parent ask me about a small purple-ish circular appearance on the white of the eye.  Typically these areas are seen under the eyelids, but can appear anywhere on the white of the eye.  In many cases, they do appear to have a slight elevation over the area that is purple-hued (commonly 1-2 mm in size).  The good news-- if your eye looks like this, it is all very normal:

Via

A zoomed-in look via

A nerve loop of Axenfeld is a normal, often pigmented loop found in the sclera (white ocular tissue) where the posterior ciliary nerve comes very close to the scleral surface before it loops back through the sclera and then into the ciliary body.  In many cases there is a slight elevation to the area as the nerve loops back into the scleral tissue.  The pigmentation of the area may increase with time, and is commonly faint, giving a "purple" appearance instead of brown or black.  These areas can never result in melanoma, or any other cancerous or infective condition, and do not need treatment.

Unfortunately, many of my patients fear that these areas are signs of damage from pencils being poked at the eye by a classmate (usually a colored pencil of course).  Apparently pencil poking is still quite common in today's younger generation.  And apparently my office is not the only eye care specialist that gets these questionable pencil foreign body questions.  There are multiple reported cases of these normal nerve loops being mistaken for entrapped graphite pencil tips.  

Sigh of relief, if you have this, you are just a normal person after all.   But if you get poked by a classmate's pencil, probably best to still get it checked out by your eye doctor!