The rock that is known as Mushroom Rhyolite or Mushroom Jasper is found in several areas northwest of Phoenix, Arizona. The rock gets its name from the repeating gray pattern that sometimes looks like a mass of growing mushrooms. The formation is an atypical thunder egg formation where most of the thunder eggs did not completely form.
Celtic knots are a variety of knots and stylized graphical representations of knots used for decoration, used extensively in the Celtic style of insular art. These knots are most known for their adaptation for use in the ornamentation of Christian monuments and manuscripts, such as the 8th-century St. Teilo Gospels, the Book of Kells and the Lindisfarne Gospels. Most are endless knots, and many are varieties of basket weave knots.