The fan shell or fan mussel (Atrina pectinata) is a remarkable species which can grow to up to half a metre long.
The latest video to have been taken of the shells was shot in the 175m-220m depth range.
The shells were located during routine monitoring in the Small Isles by researchers from Marine Scotland.
The footage has been passed by the Scottish Government to the Scottish office of the Marine Conservation Society.
“Prior to this discovery only fourteen live specimens around the United Kingdom, and just three from Scotland, were reported,” says the MCS, which is the UK’s lead partner for the Fan Shell Biodiversity Action Plan (BAP).
“Only two of the three Scottish reports have been photographically verified, one of which was a transplanted specimen that has since disappeared.”
Pictured is one of the previous Scots recordings.
"Fan shells had previously been reported to MCS from the Small Isles, brought up as by-catch in fishing gear, and this footage provides evidence they are on the seabed in the vicinity,” said Calum Duncan, MCS Scottish Conservation Manager.
The MCS, added Duncan, is “working with Marine Scotland to consider how we can ensure the protection of this new population [from bottom-trawling] using the powers contained in the Marine (Scotland) Bill."