His Jewel is the Square and Compass with the Sun in the middle. The sun signifies that his position is on the lower level, to the right of the Worshipful Master in the east.
His duty is as messenger of the Worshipful Master, hence he does a lot of walking.
The Senior Deacon of a Masonic Lodge is an assistant officer of the Lodge. The Senior Deacon's principle roles are to welcome and escort both visitors and candidates into the lodge and introduce distinguished visitors.
It is his duty to assist the Worshipful Master and carry orders between the Worshipful Master and the Senior Warden. During degree rituals, he guides the new candidate and conducts him around the lodge room.
The Senior Deacon's position is similar to a Manager. The Senior Deacon of a Masonic Lodge is an appointed officer of the Lodge.