schmutzdecke n.— «Most of this gelatinous growth and of the deposited sediment collects in the top half-inch or so of the bed, and combined form what the Germans call schmutzdecke, which term has been adopted in this country. This...
fairy ring n.— «Some sediment dweller has built its mound hard against a nodule. And on the left is a “fairy ring” of unknown origin that seems to be slipping and perhaps rolling nodules into its moat.» —“Why are there...