Examples of detectable evidence of vestigially metameric structures include branchial arches and cranial nerves. Making metameric matches using reflective materials is more complex. This type of color matching is known as metameric matching. The peripheral nervous system segmentation is highly influenced by the metameric mesodermal somites. Ventral region is mainly black, with metameric pairs of light greenish markings. Chordates are also bilaterally symmetric, and have a coelom, metameric segmentation, and circulatory system. The ventral nerve cord itself is a chain of (metameric) segmental ganglia, some compressed. At 5000K color temperature the metameric error is negligible. Therefore, metameric fibres cannot be distinguished neither macroscopically nor microscopically. In animals, metameric segments are referred to as somites or metameres. Centipedes are elongated metameric creatures with one pair of legs per body segment. Metameric matches made between two light sources provide the trichromatic basis of colorimetry. The creature appears to be metameric, with each metamere having three lobes, like later trilobites.