Arrowhead/Artifacts in FL rivers

I have found several shark teeth in Gainesville. The biggest is about 2 1/2" and found it digging up a gas leak at work. The biggest point that I have found was at work also. I was walking around a new construction site at lunch and found this killer point and as I picked it up, found out that it had been broken in half by a dozer. A week later to the day and 200 yards away I found the other half a perfect match. When you put them together you could see the crack. It was 7 1/2" long...