If you like, you can cut out or punch out black dots and attach these with tape to resemble “coal.” small black buttons will work just as well.
Other additions can include smaller dimension balloons known as 160s or black pipe cleaners for arms. (If you use pipe cleaners, be careful as the wire can puncture the balloons.) You can also cut out a hat from black construction paper. Feel free to use your imagination to dress the little fellow up.