Scrimshaw pendant from an estate sale

I came across this scrimshaw pendant in the estate sale of a Nagel beverage company heiress in Idaho. The piece appears to be either ivory or bone, but I am thinking maybe ivory due to graining and yellowing of the piece. The artist has signed N. Clark. I found another piece from the same artist on the internet, but the ship's detail was more elaborate in that piece; which makes me think that this one may have been an earlier practice piece.

Can someone help me with artist information, approx. age, ivory or bone? Thanks

Fair