To be honest, I’ve never paid much mind to deveining shrimp. My parents often fixed them with the shells on and added them intact to other dishes. I’m sure there were plenty of times when they deveined them, too, but I never seemed to notice.

Then one evening I invited my grandmother over to my apartment. In a turn of tables I was serving her dinner that night—camarones veracruzanos, or shrimp in a fresh Veracruz-style sauce with olives and capers.

We chatted as I reduced the sauce and readied the shrimp, peeling them in the sink as she sat sipping wine at the bar. “Aren’t you going to devein them?” she asked. My facial expression must have given away my cluelessness, because she smiled and hopped off her stool to walk around and show me how to do it.

Deveining is a common step in the process of cleaning shrimp to cook, in which you remove the shrimp’s gastrointestinal tract, also called the “sand vein” or, most crudely, “poop chute.”

There’s nothing wrong with eating it, but some people prefer not to, and it makes for prettier and cleaner presentation. It can be gritty, and some find it unpleasant.

It won’t hurt you if you decide to skip this step—the vein doesn’t have much flavor (I would liken it to a subtler version of the tomalley in lobster, actually) and isn’t harmful to your health. But, especially when serving guests, it’s considered better form to go without it.

There are a couple of different ways to devein—you can do it with or without removing the shell, depending on how you’d like to cook your shrimp. As my Nana worked through a pound showing me the most common method (described below), she wished I’d had a shrimp deveiner, a tool that we’ll look at more tomorrow. She ended up sending me one in the mail the next week. Good ol’ grandma.

To devein shrimp without a special tool, peeled (most common):

Step 1: Peel your shrimp by pulling the legs away from the body and then cracking and pulling away the thin shell that surrounds the body. You can remove the tail or keep it on, depending on your serving style and preference.

Step 2: Run a paring or other small, sharp knife in a straight line down the center of the shrimp’s back. This is really intuitive to do—the knife seems to almost find the line by itself. The vein will be exposed.

Step 3: Use the tip of your knife, your hand or running water to pull the vein away from the body and discard.

To devein shrimp, shell-on:

Step 1: Use a toothpick or the tine of a fork to pierce the shrimp right in between the tail and body shell. Push it through, underneath the vein, and then pull up and pull out the vein.

Other notes:

The shell-on option allows you to hold onto all of the yummy juices and fats in the shell and head (if it’s on) which makes for great sauce and soup. It’s also much quicker and easier than peeling and slicing each shrimp.

But if you’re serving cocktail shrimp or putting them over a salad, the first option might work better for you. If you do peel your shrimp, throw them into a stock pot and make yourself a batch of stock for later.

Most of the time, the vein in shrimp is a clear tube filled with a tiny string of dark matter, but sometimes it appears milky and orange or pink. I’ve wondered if this is a sign of infection or some other ill in the shrimp, but turns out it’s just a female with roe.

So, there are the basics on the shrimp vein and devein. We’ll look at a couple of special shrimp-cleaning tools tomorrow, which make the process even easier.