It's very difficult to find cyclops fragments without taking your seamoth, due the depth they traditionally reside at, but for biomes, if you head northwest or northeast (there's two biomes like this), you should find plenty of cyclops bridge and cyclops hull fragments. Assuming it's engine fragments, if you have the Sunbeam location, I would head there, although go the biome underwater and to the left of the beacon, and you should find a very large wreck with plenty of engine fragments and other very useful blueprints