Dig Alderney has discovered part of an Iron Age round house in its latest excavation.
Initially, the most recent dig had not revealed much archaeology but this latest find will offer a target for future excavations.
The team was hoping to find more evidence of Iron Age and Roman Alderney in the trio of trenches that they opened on Les Hugettes.
A pair of trenches were also positioned along Les Mielles to seek more of the large Roman building discovered in 2017.
Dr Jason Monaghan said: "What came as a surprise was the very late date of the pottery found beneath the floors of the building.
"It seems that it was not constructed until the 4th Century AD and was modified even later by the addition of crude drystone walls.
"Some of the pottery in the latest layers may prove to be post-Roman."
Other finds from this dig include 850 shards of Roman pottery with most from the 3rd and 4th Century, a bronze coin - of the Emperor Valens AD364-367 and a silver coin of Caesar Valerian II AD255.