Information below from wikipedia....
Cold-water coral mounds have been identified in the region, They are currently being researched. Rockall lies near the Darwin Mounds, deep-water coral mounds about 185 km (100 nmi or 115 mi) north-west of Cape Wrath. These corals are long-lived and slow-growing; a justification for designating Rockall and the Rockall as a Marine Protected Area.
Atlantis : The walls were constructed of red, white and black rock quarried from the moats, and were covered with brass, tin and the precious metal orichalcum, respectively.
Rockall: is made of a type of peralkaline granite that is relatively rich in sodium and potassium. Within this granite are darker bands richer in the alkali pyroxene mineral aegirine and the alkali amphibole mineral riebeckite. The dark bands are a type of granite that geologists have named "rockallite", although use of this term is now discouraged. In 1975, a new mineral was discovered on Rockall. The mineral is called bazirite, (chemical composition BaZrSi3O9), named after the elements barium and zirconium.
Rockall: There have been disasters on the neighbouring Hasselwood Rock and Helen's Reef (the latter was not named until 1830).
- 1686 — a Spanish, French, or Spanish-French ship ran aground on Rockall. Several men of the crew, Spanish and French, were able to reach St. Kilda in a pinnace and save their lives. Some details of this event were recounted by Martin Martin in his A late voyage to St. Kilda, published in 1698. The ship was perhaps a fishing vessel based in the Bay of Biscay and bound for North Atlantic cod fisheries.
- 1812 — survey vessel Leonidas foundered on Helen's Reef.
- 1824 — brigantine Helen of Dundee, bound for Quebec, foundered at Hasselwood Rock; "the crew left most of the passengers to drown, including seven women and six children".
- 1904 — DFDS steamer SS Norge, 3,318 tons with 727 emigrants and a crew of 68, bound for New York on 28 June 1904; 635 lives were lost with the 163 survivors being taken to Stornoway.
Atlantis:...And the island of Atalantes which was greater than Africa and Asia, as Plato says in the Timaeus, in one day and night was overwhelmed beneath the sea in consequence of an extraordinary earthquake and inundation and suddenly disappeared, becoming sea, not indeed navigable, but full of gulfs and eddies
Atlantis: The 4th century historian Ammianus Marcellinus, relying on a lost work by Timagenes, a historian writing in the 1st century BC, writes that the Druids of Gaul said that part of the inhabitants of Gaul had migrated there from distant islands. Some have understood Ammianus's testimony as a claim that at the time of Atlantis's actual sinking into the sea, its inhabitants fled to western Europe; but Ammianus in fact says that “the Drasidae (Druids) recall that a part of the population is indigenous but others also migrated in from islands and lands beyond the Rhine" (Res Gestae 15.9), an indication that the immigrants came to Gaul from the north (Britain, the Netherlands or Germany), not from a theorized location in the Atlantic Ocean to the south-west. Instead, the Celts that dwelled along the ocean were reported to venerate twin gods (Dioscori) that appeared to them coming from that ocean.