Here's what it might mean, depending on the context:
* "Lumps of rock": This would refer to irregular, solid pieces of rock. It emphasizes the lack of a smooth, defined shape.
* "Lumpy rocks": This would also refer to rocks with uneven surfaces and possibly bumps or protrusions.
* "Lumps and rocks": This could be a way of describing something that has both irregular lumps and smooth, solid rocks.
To understand the intended meaning, you'd need more context. For example, what is the sentence or the situation where you heard this phrase?
