A Peaberry is typically considered a defect. It occurs when a coffee cherry only contains one seed (bean).
Although a Peaberry is typically considered a defect, occurring in about 10% of coffee cherries.
Peaberries tend to be smaller, denser and sweeter than a typical coffee seen(bean). This is because they did not have to share their space so they were able to round more and absorb additional sweetness from the cherry.
Many Peaberry coffee's are high sought after for their unique characteristics and rarity.