What is this flat, gray bug?

There are on my garage wall in south Florida. They are pointed on both ends and rounded in the middle, flat to the wall, smaller than a thumb tack, appear to have no legs but have a small yellow/orange thing sticking out of one end...kinda like a clam :) They attached themselves in the cracks of the stucco on the walls inside my garage. You can easily sweep them down with a broom...