Malm vs Mulm - What's the difference?
malm | mulm |
A soft, crumbly, chalky, grayish limestone.
An artificial mixture or chalk, clay, and sand, from which bricks are made. The resulting bricks have a light brown or yellowish color.
(Webster 1913)
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The sludge that collects at the bottom of an aquarium, consisting of fish excrement, decaying plant matter, and other assorted dreck.