Stinging freshwater Hydroids mussles and beetles

[popolarbear]

this weekend i got stung by what one person i talked to claimed to be a stinging freshwater mussle. aparently in some areas tiny mussles will sting you. im familar with stinging aquatic beetles, but i think it would be difficult to get into a situation were youd get stung.(perhaps picking up aquatic weeds, i have gotton stug in this method, and disscovered these beetels the first time. typicaly white carpace, and actualy a hemenoptera and not a beetle, but they look like a beetle).
situation was, i think, ... i grabed a large bolder to hold my position while in strong river current and got stung. the pain throbed and grew and encased my whole hand before hours latter dissapearing...
anyone hear about such a thing??