Consider this your official warning: Shad roe season is coming.

In a 2010 tribute to the seasonal delicacy, the Wall Street Journal described the "lost ingredient" as "reserved for a piecemeal society of culinary anthropologists." But shad roe never courted obscurity in Charleston, where the herring egg sac has attained classic status.

If the word "roe" conjures images of caviar, shad roe will come as a surprise. The crescent-shaped lobes look and taste more like liver (and, like liver, are often prepared with bacon.) It's frequently served for breakfast, in accordance with 19th-century practice, alongside grits or eggs.

That doesn't mean there's anything humble about the tremendously rich roe, left in the wake of thousands of American shad on their way from the Atlantic Ocean to the inland streams where they spawn. "There are some people (in Charleston) that can cook it and serve it properly on proper china," says event planner Mitchell Crosby.

For eaters who don't score an invitation to a dinner party where shad roe is being served, local seafood markets carry it, and restaurants, including The Grocery, Hominy Grill, FIG, McCrady's and SNOB, usually make room for it on their menus.

Shad roe season begins in March. It lasts just a few weeks.