idotoast 的鑑定

sensu lato
Typical-form Corbicula found on land, in part of a stormwater drainage system. The 2nd photo gives context to the pond and the midden and how they are connected, although a few hundred feet apart. The 3rd photo gives context closer to the midden, where some sort of drainage pipes run underground. There’s a consistent flow of water and Corbicula through the mud, along with Unionid fragments (maybe) and Planorbella snails. The midden is in a ditch, a few feet above the drainage. Perhaps a really strong storm in the past displaced a lot of Corbicula bringing it up here, or perhaps many stray shells were brought here over time by strong currents. Either way, the pipes must’ve overflowed because the shells otherwise couldn’t have gotten here.

Shells of bivalves and snails can be found throughout the ditch between the midden and this area where rainwater flows directly into the pond

The midden also surprisingly consists of Sphaeriids. Both Euglesa and Musculium are present here, although in small amounts. I have yet to find any Unionids or Unionid fragments