Sometime around 1900, an eruption on Santiago Island in the Galapagos led to a field of pahoehoe lava covering the southern part of the island. This is a picture of a small section of that lava showing the interesting patterns in the hardened lava.
Hornitos are formed in lava flows when a small opening releases a small amount of lava. This is a hornito in the lava flow on Santiago Island in the Galapagos.