General abundance: Common
A number of web sites refer to it as a "Fin/Spine."
This leads me to believe that many are not sure
whether it is a spine or a fin.
It's a spine. Fins are flesh, and would not likely be
preserved. Spines are often located behind the
I think the question is which fin is it?
The options are the paired fins, those being the
pectoral fins and the pelvic fins, or the unpaired fins,
the caudal fin, the dorsal fin, and the anal fin. The
caudal fin is the tail. The dorsal fin can be multiple,
that is, from the anterior you have the first dorsal fin,
the second dorsal fin, etc.
The anal fin can also be multiple and is counted the
My best bet is that the marvelous Easter egg you
broke open and posted it's picture contains a dorsal fin.
Phylum Chordata (sharks & bony fish)