They are a cluster of 5 vertebrate bones of some somewhat sizable animal. Without large protrusions for rib attachments, I'd guess it was a fish. I'm no bio-person, so that is as far as I can take it. If after soaking in vinegar or other acetic acid, there is no gelatinous fat/protein residue, it could be a fossil. If a residue is left, it is evidence of a reasonably recent death. Good luck on your quest.
The mineral is calcium phosphate. Not a shark. Their vertebrae are usually composed of cartilage which is sometimes calcified but very rarely ossified, and these appear to be made of bone. These are probably are the vertebrae of a large teleost fish, something at least 5' long. Given your location that narrows down the possibilities. Likely candidates would be halibut, tuna, or swordfish.
Yeah, I'm leaning toward shark now too. My point of reference for shark vertebrae was the Cretaceous Squalicorax, where the centra are more flattened, like coins or poker chips. But Remi's photo set me straight.
I talked to Steve Turnbull. He recommended that you talk to Donald McAlpine, the Zoology Curator of the Museum of New Brunswick, here in Saint John. Don, is certainly the foremost authority in the region and should be able to give you/us an answer. Don can be reached at [email protected] or at (506) 643-2345.