A <a href="https://en.wikipedia.org/wiki/Southern_three-banded_armadillo" class="extiw" title="en:Southern three-banded armadillo">Southern three-banded armadillo</a>, just about completely curled up in his protective shell. You can see here how his shell and head and tail all fit together to make a perfect ball.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/48439369@N00">Tim Pierce</a> from Berlin, MA, USA
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/qwrrty/10432292444/">Southern three-banded armadillo</a>