From the case:
Cotton on a cotton plant (photo)

Cotton on a cotton plant.
Original file: https://commons.wikimedia.org/wiki/File:CottonPlant.JPG
Modifications: cropped.
This image or file is a work of a United States Department of Agriculture employee, taken or made as part of that person's official duties. As a work of the U.S. federal government, the image is in the public domain.
Case Discussion
Cotton wool appearance of bone is one of the many signs of Paget disease.