According to TFA, “a marine ecologist for Fisheries and Oceans Canada” said it “contains no biological material”, which would rule out the most usual globster suspects (rotting whale chunks), and presumably most foodstuffs (so it isn’t actually dough). Someone else tested it and discovered that it was not a congealed petroleum-based lubricant or fuel. That leaves a lot of possible suspects. My guess at this point would be a chemical product that was jettisoned by some dishonest corp as being contaminated or unfit for purpose, and broke up into chunks in the water. 🤔