That is INTERESTING ♦♦ I've Taken #marine #biology, & yet I didn't know about this .
It is a Really colorful freak of #nature, isn't it? Wow - gorgeous colors.
Definitely I Do recall learning about the hermit crab. Just not about the King Crab ! 
PEEPS who might enjoy reading up about Puget Sound (WIKIPEDIA):
P.S.
I've spent time up in Washington area (and Have been out on Puget Sound & up to Friday Harbor Island for a #Family Reunion) -- but never went diving there -- You're fortunate indeed, & am a bit envious