Ok so i'm 99% sure its a cow femur. A few months back my neighbor was cutting cow legs on a saw ( a whole different story) and one leg got stolen. We assumed it was another neighbor dog. That dog comes onto my yard frequently so i think the dog stole the leg, ate the meat and put it under my...
Here is a better picture
http://www.instructables.com/image/FVMTNYWG5W7CJIK/Continuous-Rotation-Servo-no-555-timer-needed.jpg
form Continuous Rotation Servo (no 555 timer needed!)