Some bulbs have the trick of forming their new bulbs deeper and deeper year after year. In some tulips the new bulb is formed at the bottom of a downward growing growth called a dropper.
Here you see something similar in little Colchicum parlatoris after several years of pot culture. The last year or two it experienced some neglect, and as a result its bulb (in this case, technically a corm) is run down and small. What's interesting to me about this is that the old corm tunics have been preserved. The newest growth was at the left hand side of what you see above - everything to the right is old growth from prior years (and none of it is alive).
After taking the picture, the new corm was repotted in better soil and near the surface. With luck, I'll be repeating this exercise in a few years, but I hope when that time comes the new corm will be back to its normal size. It's shown above on a quarter-inch grid.