A flame shell, Limaria hians,is a striking bivalve which resembles a scallop

Scallop

A scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are a cosmopolitan family, found in all of the world's oceans. Many scallops are highly prized as a food source...

 but has a bright orange fringe of filaments emerging from between its shells. Their distribution is primarily in the west coast of Scotland

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 from the sublittoral (below low tide) down to 100m, although there are patchy records of them appearing in more southerly regions of the United Kingdom. There is a well-known colonies on the sea bed in Loch Carron

Loch Carron

Loch Carron is a sea loch on the west coast of Ross and Cromarty in the Scottish Highlands. It is the point at which the River Carron enters the North Atlantic Ocean....

below Strome castle.

They make sticky threads to bind stones and shells into a felt-lined nest. Holes in the reef allow fresh seawater to flow through, preventing stagnation. They can't be seen unless the mat-like nest is disturbed, or torn open by an anchor or a hand.