I have SO MANY SHARK TEETH!!!! About 384!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! But we had never found the cartilage.
Today, we did! We drove to Purse fossil beach (Nanjemoy formation). I had started raining terribly hard. But we did not turn back. We decided to have an adventure in the rain. It was pouring and we did not bring any rain gear. We did not care. We made rain ponchos from emergency blankets that we had in the car. And we went to the beach.
The best time to look for fossils is in the rain or after. You can find much bigger teeth than usual. I found a tooth immediately. Then, I found this SHARK VERT! Some people think that cartilage does not fossilize. But it is not true. Places where cartilage is dense can become fossils. The vertebra, or fins, or nose, or the tiny scales that help sharks swim fast.
We also found a jaw piece. It might be from a drum fish or from a puffer fish, or even crocodile, but it is not clear. Can you identify it?!
We were not there very long, but collected 34 teeth, some of which were large. One of them had a number 4 “scribbled” on it. (Hmmm….) 
What a lucky day you had today!
384 teeth!! Wow!! Maybe you can ask someone in a museum whose jaw it is? Like a paleontologist!