What ya think it is??

Saw this floating about a mile off our platform. At first sight it resembled floats from a chopper. We sent our boat out to retrieve it. It looks like it's made of aluminum and pretty beat up. It's doesn't look like its been in the water too long though. I'd say its about 6'-8' long, and about the same diameter of a 55gal drum. We'll be pulling it up later and getting a better look at it. I'm guessing some sort of buoy, maybe something from a survey boat. Not real sure! The back end of it appears to be made of a different material. It's not buoyant, and it sways with the current. Any ideas?
http://i714.photobucket.com/albums/w...ps326ce343.jpg
http://i714.photobucket.com/albums/w...ps2c50127e.jpg
http://i714.photobucket.com/albums/w...psa0fd5fbd.jpg
http://i714.photobucket.com/albums/w...psdaff5b39.jpg

Just finished taking it out of the water, back end has fins on it. Had about 40' of big chain connected to it with what looked like half of a pipe clamp.
http://i714.photobucket.com/albums/w...psc4032899.jpg