Swan pond is shallow with a sandy bottom, ideal for Large Mouth Bass. The sandy circles are spawning areas made by the male bass for the female to deposit her eggs.
The 57 acre pond is like a giant aquarium with clear water to see the variety of aquatic plants.
These small clam shells were in the scooped out spawning circles. I am not a fisherman but my guess would be the bass put them there for baby fish to hide among.