Nodule (noun)

A small, usually rounded, solid lump of tissue or a mineral deposit in a human or animal body, or a small, rounded or irregular lump of mineral matter in rock.

Origin:

The word nodule comes from the latin word "nodulus" which means "a small knot." it refers to a small, usually rounded, solid lump of tissue or a mineral deposit in a human or animal body, or a small, rounded or irregular lump of mineral matter in rock.

Examples:

1. The doctor found a nodule on my thyroid.
2. The nodule on his lung was malignant.
3. The geologist found a nodule of gold in the rock.
4. Nodules of iron ore are commonly found in rocks.
5. The nodules on the coral reef are homes to many small creatures.