muck vs sapropel

muck and sapropel both are nouns.

Word	Noun	Adjective	Verb	Adverb
muck	Yes	No	Yes	No
sapropel	Yes	No	No	No

As nouns, sapropel is a hyponym of muck; that is, sapropel is a word with a more specific, narrower meaning than muck:

muck: any thick, viscous matter
sapropel: sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans

muck (noun)	sapropel (noun)
any thick, viscous matter	sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans
fecal matter of animals

muck (verb)	sapropel (verb)
remove muck, clear away muck, as in a mine
soil with mud, muck, or mire
spread manure, as for fertilization