Marine invertebrates vary in their timing of reproduction, just like most organisms on land. Even though humans may find the temperatures in the Sound pretty cold year round, the invertebrates are sensitive to both the temperatures and the change in food availability in the water. Several species are reliably reproducing on the beach every year and I make a note of when I observe them. Many of these observations can be made without a microscope, because the egg masses of molluscs are large (those squid ones are finger-sized). The larvae themselves are in the water and must be captured with a plankton net. I still don’t have a clue about those gastropod egg masses (the jelly is water-clear, and the tiny chartreuse-colored eggs are laid in really neat, straight rows) in the last image so I will need to do a bit more reading. (Ironically the bivalves we’re growing do not lay egg masses, but release their eggs and larvae freely into the water, so I don’t see those on the beach.)
An early spring gathering of oyster-drilling whelks 
The spring cohort of juvenile barnacles (covering everything) 
Early summer egg cases of the moon snail 
Early August observation by the Tacoma Upward Bound students of a squid egg case washed up on the beach 
Late summer gastropod egg mass laid on the edge of bivalve shells