marine snow

marine snow noun

1. small particles of organic biogenic marine sediment, including the remains of organisms, faecal matter, and the shells of planktonic oganisms, that slowly drift down to the sea floor

Collins English Dictionary – Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012