What in the Worm?

On April 14, while walking at the edge of the water in Mission Beach, I came across a strange creature that had washed up on the sand. Unsure as to whether or not this tangerine-sized, coral-tinted, purple-veined thing was poisonous (and envisioning alien projectiles reaching out to grab my camera upon touching it), I decided against picking it up. Instead, I gently poked it with a stick to see if it was soft or hard. It was soft and had a white funnel-like protrusion at the end not visible in the photo. I snapped a few photos just before the next wave embraced it and pulled it back to sea.

I spent the next several days trying to figure out what I had seen. I stopped several lifeguards as they drove by me on subsequent walks. I showed them the photo. “Can you tell me what this is?”

“Hmm...never seen that before…the oceans are changing,” said a Mission Beach lifeguard.

“Looks like some sort of mussel,” said another lifeguard. “He probably lost his shell, got washed up and all stressed, thinking, I can’t make a shell here and panicked.”

It was unanimous: six lifeguards equally stumped. I then emailed the photo to Scripps Institute of Oceanography. Two days later, I got this response from Fernando Nosratpour, assistant aquarium curator at the Birch Aquarium:

“I believe the animal in your photo is a peanut worm,” said Nosratpour. “I'm not sure what species. Peanut worms bury themselves in the sand and can retract so that they take on a peanut-like shape. I'm guessing — because the animal you found is exposed to air — it's probably pretty stressed and has retracted into a ball shape. This shape may help it conserve water until the tide comes up. Normally, these guys live under the sand and siphon water/food through their tube burrow. The one you found is quite a bit larger than the more common ones we find locally.”

Google images seem not to support Nostratpour’s peanut-worm designation. Can you help solve this marine mystery?