Sea grapes are a marine algae that look much like their landlocked namesake. That is, they are green pearl-like orbs that cluster tightly along underwater vines. And sea grapes, like regular grapes, are a popular snack food too… albeit of the saltier variety. Fans of the briny delicacy enjoy the way the shiny pearls POP when chewed. It makes one wonder whether sea grape juice might have some appeal? ‘Twould leave the drinker with sour grapes, I suppose.