I recall diving when rock walls were covered with sunflower stars (Pycnopodia helianthoides), as in this older photo from 1998. These massive predators can grow up to three feet across and weigh eleven pounds, with a range from northern Alaska to northern Mexico.
Since then the sea star “wasting disease” that has taken place is one of the biggest wildlife die-offs ever recorded and ranges from Alaska to Mexico. Unfortunately, the disease is still prevalent and I’ve noticed affected sea stars while diving.
The following CBC article offers more information on the subject: