What is this mystery object that washed up on a South Carolina beach?

This mysterious large object washed up last week on Seabrook Island in Charleston County, South Carolina. Apparently it has the consistency of foam and does not seem to contain any metal. The Lowcountry Marine Mammal Network posted this photo of it to their Facebook page generating many fantastic theories and a few boring ones. From UPI:

Some have suggested the object resembles the shape of a damaged marine buoy like those used by the University of North Carolina at Chapel Hill.

Seabrook Island officials had the object removed by a truck and trailer, but they have not commented on the identity of the unusual piece of debris.