At the end of 2008 a party of school children accompanied by a local man showed us some pieces of flint tool picked up from the Worm, one of which he gave us.
None of us being archaeologists we have been reluctant to publish the accompanying photo until now. However Peter Francis, a Gower warden of 20 years and an experienced caver, does think that it is a flint tool from the Mesolithic age ("Mesolithic" is derived from the Greek words mesos, meaning "middle", and lithos, meaning "stone"), covering the period 8500 BC to 4000 BC.
We have contacted Miss Elizabeth A. Walker, Collections Manager/Curator of Palaeolithic & Mesolithic Archaeology at the National Museum Wales, Cardiff, who is happy for us to take the artefact there for closer inspection. From my understanding such finds should be reported even if just for cataloguing.