A standing, rain-fed pool on the floor of the tree fern Ola'a Forest near Volcano, on the island of Hawai'i. In this area of recent volcanic activity, the newly formed volcanic slopes are too porous to allow the development of permanent streams. Instead, pools such as this with a fine ash bottom, provide an alternative breeding habitat for Megalagrion calliphya , a species that otherwise prefers to breed in slowly moving stream pools.