There are two small bones in the first metatarsal joint.

These are called sesamoid bones.

They can move around with stress or crack and break.
I have broken ones on both feet.

When they inflame the tissues around them, it is called sesamoiditis. This shows up on Xrays.
http://www.myfootshop.com/detail.asp...oid%20Fracture

I've had one injection in my left foot over the years for this,
and that foot seems larger in the ball area than the other.
But I cannot feel any "knots" or lumps in them.

I am very careful about shoe choice, because of this.

Some of Colt's lumps don't seem to be in this area, unless I am mistaken. Some of his are on his toes... more like spurs. But it can be hard to visualize them from writings on the net.

The feet have little extra tissue, so deposits of calcium or spurs appear easily, and can be felt. I've seen gamers who play lots of hours with those controllers get spurs on tendons in the hand. Typically they resolve when rested for a while.

One should always keep an open mind about mechanical issues with the feet.

This website I found is very good, showing the bones, nerves and blood supply. There are many parts of this website worth looking at. I found an alternate way to lace my shoes to take the pressure off my sensitive instep there!
https://www.northcoastfootcare.com/p...echniques.html

http://www.northcoastfootcare.com/