This steep, rocky park has beautiful examples of Franciscan chert. The rocks are home to a variety of plants, including two native succulents, dudleya and stonecrop. Stonecrop is the host plant for the San Bruno elfin butterfly, a federally listed endangered species. Rocky Outcrop is a small park, but it offers habitat for a variety of wildlife. The brightly colored, nickel-sized green hairstreak butterfly is found in only two regions within the city: the coastal bluffs of the Presidio, and along the ridge of Golden Gate Heights, here and in the nearby Hawk Hill natural area. The goal of the Green Hairstreak Project is to reconnect and expand the populations found here so they can interbreed; the group leads spring walking tours of the neighborhood to look for the butterflies. There are no designated trails in the Rocky Outcrop natural area, but it can be viewed from Pacheco Street.