A sloth can turn its head almost 180 degrees, as it has an extremely flexible neck.
From the Nature Institute in New York:
The sloth’s neck is not only unique in its flexibility, but also in its anatomy. Mammals have seven neck (cervical) vertebrae. The three-toed sloth usually has nine and the two-toed sloth has between six and nine cervical vertebrae.
I have a very good and beautiful friend over in the USA for a few years of work. I miss her a lot 
She sends me postcards from all over the country, I get very jealous! Last week I got this cute little letter and sloth sticker present in the mail, which is now on my fridge. Snail (or sloth?) mail is so underrated in these days of immediate communication!
