Green Slime
Acidic, devours flesh, organic material, and metal on contact.
Covers 5ft square, clinging to walls, floors, and ceilings. Has blindsight out to 30ft, drops from walls and ceilings when detects movement below. No other ability to move.
Avoid being struck with a DC 10 dexterity save.
Take 1d10 damage on contact. Take damage again each turn of continued contact until it's scraped off or destroyed.
Deals 2d10 damage against wood or metal each round, and any non-magical item used to scrape the slime off is destroyed.
Destroy with sunlight, cure diseases, cold, fire, or radiant damage.