Time to dust off the microscope and see what I can see.
This creature reminds me of a fresh water shrimp but I don't think it is:
So far it doesn't match anything in the references I have.
The nearest I've got - it looks to be an amphipod. It may have been damaged when I sucked up some water from the pond in a small syringe. The large end of the creature should be the head end.