Answer: They're bones in the arm.
Everyone who answered got it right, which is everyone from last round except EricBess. So he falls behind...
Scores:
DarthFerret: 2
Limited: 2
Melkor: 2
Mooseman: 2
Oversoul: 2
Ransac: 2
rokapoke: 2
sageridder: 2
TomB: 2
train: 2
turgy22: 2
EricBess: 1