You can get a fish that eats them. If you keep your water cleaner or feed in a cleaner manner it will reduce the population. Maybe running a 30 micron filter sock a couple of times a week will help.
Sponges are filter feeders so if you reduce their food source it will limit their population.
Mike an explosion of sponges (ex, pinecones) is a sign of a nutriant spike because as mentioned they are filter feeders...two ways to correct it or keep them in check...gettting a sponge eating fish like many species of Angels or get to the source and improve water quality.