Species with a relatively small genome, with a short generation time from seed to seed, and that are adaptable to living in captivity are appealing as experimental organisms. Even though many of these species bear little physical resemblance to humans, they do share part of our genome, so they can answer some of the questions we have about genetic inheritance and gene expression. For example, some commonly used species in genetic research include the plant Arabidopsis thaliana, with a genome size of 120 million base pairs; the orange bread mold Neurospora, a fungus with forty million base pairs; Drosophila melanogaster, a fruit fly with 170 million base pairs; and a Caenorhabditis elegans, or roundworm, with ninety-seven million base pairs.