Select the one substance that is not a rock.

 - A nutshell is made by a living thing. It is formed in nature.
 - Dolerite is not a pure substance. It is formed in nature.
 - Andesite is not a pure substance. It is not made by living things.
Compare the properties of each substance to the properties of rocks. Select the substance whose properties do not match those of rocks.
A nutshell is made by a living thing. But rocks are not made by living things.
So, a nutshell is not a rock.
Andesite is a rock.
Dolerite is a rock.