What on earth is this?
An Olla is an unglazed clay pot fired at a low temperature. This allows the pot to remain porous. The OLLA is buried in the ground with neck exposed and periodically filled with water. The water seeps into the soil at a rate that provides adjacent plants with a constant water source at the roots.
The olla method is an ancient technique of low tech, low cost irrigation used in various environments around the world.