What did Karana mean when she said ''Gulls had picked his bones clean, but I found what I had come for"?

Karana meant that the old bull's teeth hadn't been taken, and that was what she had come for. She used the teeth for spear points.

The tide was low when I reached it. Far up on the slope lay the body of the old bull. Gulls had picked his bones clean, but I found what I had come for.
Some of the teeth were as long as my hand and half its width. They were curved at the tops and some were broken, but when I had ground the best of them down with sand, I had for my work four good spear points, broad at the bottom and very sharp at the ends.