The phrase "a layer of slime" is correct and usable in written English.
It can be used to describe a thin coating or film of a viscous substance, often in a literal or figurative context.
Example: "After the rain, the rocks were covered with a layer of slime that made them slippery and dangerous to walk on."
Alternatives: "a film of slime" or "a coating of slime".
A layer of slime, in some species similar to saliva or mucus, covers the whole plasmodium.
Some, though, dismiss it as a glorified duck pond and as I'd been warned about a layer of slime on the water's surface, I abandoned my usual Neddy Merrill-style "choppy crawl" for a head held high breaststroke.
Characteristically, the entire plasmodium is covered by a layer of slime, which is continually secreted and, as the plasmodium creeps, continually left behind as a network of collapsed tubules.
It didn't take long for someone to figure out that the big Victorian house featured in Sunday's season finale of "Mad Men" — as a shaggy Depression-era brothel in one pivotal scene, with the more intense desperation of late-1960's poverty clinging to it like a layer of slime in another — doesn't look like a haunted house in real life.
And just like a real snail leaving a layer of slime across your garden path, this snail leaves a phosphorescent glow as it goes about its journey.
The fruit bodies are medium-sized, pure white, and when wet are covered in a layer of slime thick enough to make the mushroom difficult to pick up.
But when the diet contains too much starch and too little roughage, rumination all but stops, and a layer of foamy slime that can trap gas forms in the rumen.
My eyelids crack through a layer of sleep-slime and push open.
The fruit bodies (mushrooms) produced by the fungus are characterized by a chocolate to reddish-brown cap covered with a sticky layer of slime, and a short whitish stem that does not have either a partial veil or prominent dark or colored glandular dots.
A glance inside the classrooms reveals the damage the murky waters left behind: Wide cracks and holes have opened in the concrete floor, which is covered in a thick layer of slime.
Fish have a protective layer of slime on their bodies, and will become sick if this "suit of armor" is breached.
