Starfish first appeared in the fossil record in the Cambrian. The first known asterozoans were the Somasteroidea, which exhibit characteristics of both groups. Starfish are infrequently found as fossils, possibly because their hard skeletal components separate as the animal decays. Despite this, there are a few places where accumulations of complete skeletal structures occur, fossilized in place in Lagerstätten — so-called "starfish beds". By the late Paleozoic, the crinoids and blastoids were the predominant echinoderms, and some limestones from this period are made almost entirely from fragments from these groups. In the two major extinction events that occurred during the late
Starfish site and Sheffield. The new "Special Fire" decoys were set up to simulate the bomb drops of German pathfinder squadrons. By 23 January 1941 the programme had been increased to 43 sites protecting 13 town and cities and by March operational sites numbered over 100. By the end of the war there were 237 Starfish sites protecting 81 locations. One of the first decoy sites was constructed on Black Down on the Mendip Hills; it was code-named "Starfish", derived from Turner's original SF code, and built to protect the nearby city of Bristol. The Starfish name was eventually adopted to describe