Two clusters of eye spots and a gut in a smear of soft jelly.
At least 126 species of free-living flatworms dwell in the marine waters of the Pacific Northwest ... (Marine Life, Lamb and Hanby)This one is probably the Bivalve flatworm, Pseudostylochus ostreophagus, an invasive species from Japan. Like all flatworms (polyclads, referring to the many branches of the digestive tract), it has a two-way gut; there is no anus, so waste materials are expelled through the mouth, on the underside of the worm.
I was intrigued by the way these critters moved, flowing as if they were a liquid, but folding themselves over the lip of the clamshell or pushing at the "skin" of water droplets. I posted a video to YouTube: Flatworms demonstrate the slither.