It's a good thing the FishHeads don't mind getting a little dirty, because they're going knee-deep in muck with the Department of Fisheries and Oceans to find the Wavy Rayed Lampmussel, a fascinating bivalve that Leo loves because it helps keep the water clean. The search is on for the hidden river mollusk, and Christian and Sayat use special viewfinders to glimpse below the surface to seek out the mussels that bury themselves in the riverbed.