It looked like a turtle beak, but I'm not quite sure. Last time I made a guess about a turtle I was incorrect.
Anyways, here's some pictures:
And my video log of it:
Mystery Bone at Kahului Harbor
The second and third bones I found were discovered just recently! During the International Coastal Clean Up I did at Kahului Harbor Section 1.
And Bone 3:
Any guesses as to what they belong to?