Is this by the Roosevelt dog park at the AMNH?

Is it a killick?

It's a cleared and stained specimen - these things are common preparations in museum collections. The critter is fixed in formalin solution, and then the soft tissue is digested by enzymes until it is transparent and jelly-like. Cartilage and bone are typically stained red and blue, respectively.

Here's a protocol.
http://www.gobiidae.com/methods/method_clear_and_stain.htm