That's not quite right. While mud is a common ingredient in many nonclastic sedimentary rocks, it's not the only one, and not all nonclastic rocks are made of mud.

Here's a breakdown:

* Clastic sedimentary rocks are made from fragments (clasts) of other rocks, minerals, or fossils. These fragments are transported, deposited, and cemented together. Examples include sandstone, shale, and conglomerate.

* Nonclastic sedimentary rocks are not made from fragments. Instead, they form through chemical precipitation or biological processes. Examples include limestone, rock salt, and coal.

Mud is a fine-grained sediment that typically contains clay and silt. While mud can be a component of some nonclastic rocks, it's not a defining characteristic.

Here are some examples of nonclastic sedimentary rocks that are NOT made of mud:

* Limestone: Often forms from the accumulation of marine organism shells, coral reefs, or chemical precipitation of calcium carbonate.

* Rock salt: Forms through the evaporation of water in enclosed basins, leaving behind salt deposits.

* Coal: Formed from the accumulation and compaction of plant matter over millions of years.

So, while mud can be a component of some nonclastic rocks, it's not the only or even the most common ingredient. The term "nonclastic" emphasizes the formation process, not the specific composition.