Very rare here on Sanibel!
I maybe only ever found this species once before in 2017:
The two lower ones are badly chipped.
These three valves, found on December 15th, are in better shape:
5mm, found in a primarily Corbicula midden in a stormwater drainage ditch. Not Euglesa compressa. I think it’s Euglesa but Pisidium could be a possibility
I’m unsure where the water comes from, perhaps a nearby pond with a mud or gravel bottom. When the water overflows, it leads to the stormwater retention pond where I’ve previously recorded other Euglesa shells.
Found with @danieldoxin. See his observation here: https://www.inaturalist.org/observations/215123421