Although cotton was well-known and widely used in India as far back as 3000 BC, it seems to have been a late import into the western world, including Egypt. The uncultivated plant itself may have been known in Nubia in very ancient times, but the earliest extant examples of the fibre in that area are first century AD textiles. The small ball of semi- processed cotton that is reported here was found adhering to the linen wrappings of PUM II, a mummy that has been dated reliably to the Ptolemaic period. There appears to be no good explanation of its purpose there. Egyptologists and textile experts have been consulted, but this remains a unique and unexplained phenomenon.