the world > the earth > structure of the earth > constituent materials > earth or soil > mud > [noun] > deposited by river or sea > containing shells (4)
snail cod1649
A fertile mud containing shells, taken from the bottom of rivers.
snag-greet1651
(See quot. 1651 and cf. snail cod, n.)
mussel-mud1774
Mud containing a large number of mussels or mussel shells, used as fertilizer.