Simple vs Complex

A lifeform is "complex" if it is a vertebrate. Plants, fungi, bacteria, protozoans are "simple." Viruses do not count as life forms.

A substance is "complex" if it can be recognized by mundane human senses as made of one or more substances. A cast iron skillet is simple. A non-stick pan is complex: it's made of metal, with non-stick coating and likely also a synthetic handle.