This is one of the eight anchors. As the ship lays pipe, it pulls itself forward with winches. There are eight anchors, and it takes two anchor handling tugs (like the one in the picture above) working full time to keep the anchors moving as fast as the pipe lay vessel.
Because of the shallow water, the pipe lay vessel can't hold very much fuel or pipe, so it takes a fair number of boats to shuttle back and forth to keep everything supplied, but not so supplied that you hit the bottom.