A female. Notice the large pleopods (used to brood her thousands of bright orange eggs), and the small claws present at the tip of each 5th walking leg.
Under some boulders with a herd of small red shrimp upside down, and big red urchins (Strongylocentrotus franciscanus), plus a lone cucumber (Parastichopus parvimensis).
Males transfer gummy sperm packets to the underside of females. When the females ovulate, they manually fertilize them using the packet they carry around with them. It's a big ocean floor out there and one might imagine the odds of finding a male at the time of ovulation.