These guys can be tough on power plant cooling water intakes.
A guy I graduated HS with up in Michigan became a professional diver, their company made a fortune cleaning out the Cook county nuke plant intake pipes over in lake Michigan, and the intake pipes near Detroit were an almost continuous contract for them. A few years out of HS and he had a house, new car and was doing really well, all thanks to those little buggers.
One of the biggest problems with zebra mussels is they clean the water so well that seaweed and grasses explode from the sunlight getting down so deep, a major problem in itself when the shorelines start looking like the Sargasso sea.
Are these heat seeking mussels?