This was a sign on the side of the road whilst we were taking our daughter to school. My first question was "wow that is a big golden ball for the new Buddhist temple". This was met with laughter from my wife which only increased when I wanted to go to see it - it is in Nakon Si Thammarat!
The first time I saw these balls was on Macha Bucha Day at Wat Vichit Sangkaram on the outskirts of Phuket Town and then I recall seeing them at Wat Khao Rang (Wat Thepkajonjit). To the left of the Wat and I never knew what they were.
Then I found out what the balls were - information is all from another blogger - thanks Mike Rose.
These sacred stone balls, usually nine, are called ลูกนิมิต in the Thai language and are placed at the four corners and other cardinal points of the พระอุโบสถ. With one stone(often slightly larger) situated under the main Buddha image inside the ordination hall.
The actual process of burying the sacred stone balls is open to the public and may take place during a temple fair or other festivities at the Wat. People are invited to to gild the stones by buying the small pieces of gold leaf used by Thai Buddhists in their devotions and rubbing the gold onto the exposed stones.
The monks from the temple may also bury sacred objects in the recess that houses the ลูกนิมิต. When the stones have been buried markers are then built over the location of the stones.
These markers, ใบเสมา, are only built over the externally placed stones since as already mentioned one stone is inside the building under the principle Buddha statue. The external ใบเสมา and their hidden ลูกนิมิต mark the boundary of the sacred ground that is the home for the ordination hall.
Thanks Mike - I now know what they are.
The พระอุโบสถ is only used for religious ceremonies, principally the ordination of new Buddhist monks. It is normally not available to the general public to use but many พระอุโบสถ are open for viewing the religious artefacts they contain when not being used by the monks for their devotions.
Thanks again to Mike Rose for the information.