The problem with the DR part of TLDR is that you miss a lot of detail. There are more factors than just the button industry.

> To survive past the larvae stage, they must become parasites that attach themselves to fish. If the fish populations are declining, that oftentimes has an indirect effect on mussel abundance

> the U.S. Army Corps of Engineers deepened the rivers and constructed a system of dams, destroying the habitats of mussels that had evolved to live in shallower waters.

> Increasingly polluted waters also took a toll.

These little fellows are, in general, small. I guess they can get 50mm (2in), but most aren't that large and they have thin shells.

Further, I'd be somewhat afraid that creating products from them would spread the invasive species even further. The professor I worked for studied them because of their invasiveness - the lakes he set traps on were obviously spread by people. They spread easily by the water in boats - microscopic young means people don't know they spread them.