Shark Photobomb?

Mysterious creature appears during Kelly Slater's GoPro clip at the Box in West Oz

While there may be a perfectly reasonable explanation for the blob that appears at 0:17, the prevalence, and controversy, of sharks in Western Australia spreads paranoia like wildfire, prompting many to believe this is a shark photobomb of Kelly Slater’s wave at The Box. At first, we thought the surfer at 0:06 explained the blob, but upon further examination, there are no limbs or contrasting black wetsuit to what could be a white surfboard. What do you think the mysterious object in the face of the wave is?