 The I-O-F-A-C-D archaeology in archaeology, a bio-fact or eco-fact is organic material found at an archaeological site that carries archaeological significance. Bio-facts are natural objects found alongside artifacts or features, such as animal bones, charred coal, plants, and pollen. Bio-facts are passively consumed or handled by humans, as opposed to artifacts, which are purposefully manipulated. Bio-facts reveal how people respond to their surroundings. A common type of bio-fact is a plant seed. Plant remains, often referred to as macrobotanicals, provide a variety of information ranging from diet to medicine to textile production. Pollen preserved on archaeological sites informs researchers about the ancient environment, and the foods processed and slashed are grown by prehistoric people. Pollen, when examined over time, also informs on environmental and dietary changes. A seed can be linked to the species of plant that produced it, if massive numbers of seeds of a cultivated species are found at a site. It may be inferred that the species may have been grown for food or other products that are useful to humans, such as clothing, bedding or building materials. Another type of bio-fact is wood. Wood is made of cellulose, carbohydrates, and lignin. Every year that passes, a new ring is added to the trunk of tree, allowing for dendrochronological dating. Chart coal is burned wood that archaeologists are able to extract. It can be dated using carbon-14, and through other methods. Information such as local environment and human adaptation can be revealed from the chart coal To help determine the date during which a site was occupied, dendrochronological analysis can be used on wood samples. Wood that has been altered by humans is properly an artifact, not a bio-fact.