The matrices in which artifacts, ecofacts, sites and other human-manufactured features or results of past human action are found. Three typical elements of archaeological research: observed material culture, unobserved human/non-human activity. Artifacts: any portable object where form has been shaped (i. e. manufactured or modified) by way of human activity. Feature: nonportable material evidence of human activity (e. g. hearths, storage pits, postholes) Ecofacts: non-artifactual material evidence of human activity, can be further subdivided into macrofossils and microfossils. Macrofossils: visible to the naked eye, e. g. kernel of corn, can be retrieved through flotation or normal excavation procedures. Flotation device: water separation of soil matrices, used primarily to recover macrofossils, lighter materials float to the surface, caught in sieves. October 28th, 2010: e. g. pollen, phytoliths found in soils or residues adhering to artifacts, retrieved through mechanical and chemical disaggregation, visible only under high-power magnification, 200x or greater.