I can't just paint things that are cute, I find interesting, or even only things that have faces. These are from the Tennessee River system, and Cumberland River. They absolutely require clean fast moving water. They used to be the most common mussel in Tennessee, but now it is just the older ones that are left, and not many of them. Since 1918 only 3 live ones have been found in the Tennessee River. Others have been found in Cumberland River, and a few surrounding places, but only a total of 27. The increase in silt and pollution are leading to its demise.
I love shells, but I never think of them as being something I'd find in our rivers. Oregon's beaches are more where you go looking for agates rather than any really interesting shells too. It is possible to find small shells like mussels and limpets, but I've never found much in the way of impressive or exciting shells at our beaches. I love them though, they have more dramatic scenery than many beaches I've been to. It isn't nice water to swim in as it is too cold and the surf is not mild. Really, the weather can often be quite inhospitable but I prefer it to sunshine, which means I get burnt.