What is this on google maps off the coast of Long Beach?

[rriveramri]

I have found this strange area on google maps, it is about two miles off shore. It looks like some old ruins. It is under the water about 2.5 miles off the coast. It appears to be about 1 mile long by .25 miles wide. It is located at 33.669818,-118.229413 on google maps. I have searched for the answer and can not find one. I thought that someone in the diveing community might know.

[djensen]

Interesting! Clearly man-made. Looks like the bottom was dredged. That would be my guess. Why it was dredged is anybody's guess. I remember many years ago reading about harvesting manganese balls off the sea floor... Maybe?