I'm 98% certain of the species ID but have not had it confirmed by an expert. There are 180 species of Echinoderms in the Pacific Northwest, but this one seems pretty unique in the descriptions (largest seastar in the PNW; 16-24 arms -- this specimen appears to have 16), and matches the pictures of it online.
The sunflower sea star (Pycnopodia helianthoides) is a large predatory sea star usually with 1624 limbs called rays. It is the largest sea star in the world. Sunflower sea stars can grow to have an arm span of 1 meter (3 ft 3 in) in diameter.[2] The color of the sunflower sea star ranges from bright orange, yellow and red to brown and sometimes to purple, with soft, velvet-textured bodies and 1624 arms with powerful suckers.[2][3] Most sea star species have a mesh-like skeleton that protects their internal organs.[4] Easily stressed by predators such as large fish and other sea stars, they can shed arms to escape, which will grow back within a few weeks. They are preyed upon by the king crab.[4]
