A cure for "spooning" shells

When you’re cooking pasta shells, how do you keep them from “spooning”? I’ve been physically separating them, but there has to be a better way.

Bit pot of water with a rigorous boil, and stir with a wooden spoon every so often.

I toss them in olive oil before putting them in the water. It takes longer to cook them, but it keeps them from getting stuck like a stack of hats.

Here’s a previous thread on the topic: http://boards.straightdope.com/sdmb/showthread.php?p=14610010