"Its flesh was described as being like 'coarse, ill-coloured beef, entirely covered with fat and tallow and without the least resemblance or affinity to fish'. The skin, which was grey coloured and had an elastic texture was said to be about two inches thick in parts."
The Natural History Society (Wernerian Society) of Edinburgh could not identify the carcass and decided it was a new species, probably a sea serpent. Later the anatomist Sir Everard Home in London dismissed the measurement, declaring it must have been around 36 feet, and deemed it to be a decayed basking shark (basking sharks can take on a 'pseudo plesiosaur" appearance during decomposition). In 1849 the Scottish professor John Goodsir in Edinburgh came to the same conclusion. The largest reliably recorded basking shark was 40 feet in length, so at 55 feet in length, the Beast of Stronsay still constitutes something of a cryptozoological enigma.
The Stronsay beast was 55 feet long, as measured by three witnesses (one was a carpenter and the other two were farmers). It was 4 feet wide and had a circumference of approximately 10 feet. It had three pairs of 'paws' or 'wings'. It had skin that was smooth when stroked head to tail and rough when stroked tail to head. Its fins were edged with bristles and it had a 'mane' of bristles all down its back. The bristles glowed in the dark when wet. Its stomach contents were red.
Yvonne Simpson, a geneticist from Orkney, has researched the evidence and suggests that the Stronsay Beast may indeed have been an unusually large basking shark, or possibly an unknown species of shark closely related to the basking shark. The drawings of the Stronsay Beast's decayed carcass are similar in shape and size to the popular image of the Loch Ness Monster. The third pair of appendages could be a male shark's clasps, but male sharks are generally smaller than the female of the same species. There is also the possibility that the creature may have been an oarfish which has shown quite similar disparities.