News of the weird
Once in a while someone will make a rosary out of some really strange stuff -- not normal "beads' at all. I haven't seen any historical records of people doing this in, say, the Middle Ages or the Renaissance -- largely I suspect because people generally didn't make their own rosaries but bought them from a craftsman. I can certainly imagine someone collecting something like small bezoar stones, pieces of bone, etc. and having a rosary made from them -- but I'm not aware of any examples of medieval or Renaissance rosaries made of anything really un-bead-like.
Here are a couple of the ones I've happened to see on eBay.
Somehow I doubt that there is any profound meaning intended by the choice of shark vertebrae as a material. Most likely someone merely found them on the beach, decided they looked intriguing or pretty, and proceeded to make a rosary from them. The impression I get is that the "beads" are rather large items (maybe an inch in diameter) and that this is probably supposed to be a "wall rosary" rather than something for practical use.
A couple of the major bead sellers (I noticed it at Fire Mountain) are now selling a wide variety of pierced and strung shells and shell bits of various types. Here's a rosary someone made from these materials. Again I suspect this is largely a "wouldn't this be interesting" piece than anything of Deep Meaning.
This is a "wedding rosary" with two loops of five decades joined together. The Aves are ordinary beads, but the Our Father beads (gauds) are little plastic doves. It looks pretty, but I can't banish the image of sticking a big needle through each little dove as the rosary is being strung. EEEEuuuuuuwwww!