I think these rocks represent the way we interact with each other.  We rely on the strength of others, we unite to accomplish tasks, and when snow falls, a little bit of it falls on all of us.  We are all different shapes and sizes, yet we still fit together enough to form a strong bond.  Our position in the stack is usually determined by how equipped we are to handle the load.  We are carefully selected one at a time and put in place where we will be of the most benefit. Our hard surfaces remain unchanged until we collide with those around us.  Even our roles in life vary from being strong and dependable (The Rock of Gibraltar) to a symbol of an amazing history (Mount Rushmore). Where do you fit into the pile?