It is roughly six metres long and a metre high, and the only reason its interior is visible at all is that cattle have been grazing and eroding the surface over time. What has been exposed is the telltale material signature of a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically consisting of a hearth, a trough filled with water, and a mound of fire-cracked stones that were heated and dropped into the water to bring it to a boil.

What makes the Larkhill site particularly interesting is its company. Within a short distance, two further fulachtaí fia have been identified: one approximately ten metres to the west-southwest, another around forty metres to the east. This clustering around a single marshy pool is not unusual for the type. Fulachtaí fia are almost always found near water, and the concentration here suggests the location was returned to repeatedly, possibly across generations. The marshy ground that would seem to make a site inconvenient is, in fact, precisely what made it useful.