Sand can be the enemy. It burns your feet on hot days, and stings your eyes on windy ones. It gets into your car, your bag, your phone, and won't let go.

But sand is an important part of beach ecosystems, especially at the Jersey Shore.

"Sand is the smallest bits of earth that you're going to find," said Ann McElhatton, a field biologist and naturalist.

McElhatton grew up in Stone Harbor and, in 2008, started the Beach Chair Scientist, through which she runs outreach programs for schools and community events

As she sat at Cape May Point Beach, McElhatton dug her feet into the sand and made patterns deep into the grains with her hands. The sand there is coarser, even rocky, compared to that of other Jersey Shore towns because the beach is on the Delaware Bay. The rocks aren't worn down through endless cycles of waves.

"Somewhere, some sort of rock formation had broken down to make these pretty pebbles," she said, plucking through the rocks in the sand.

Sand is different wherever you go. Our sand at the Jersey Shore comes from two large sources: rocks and shells.

"Clams and scallops and oyster shells build up seashells by absorbing calcium in the water," said McElhatton. "When those shells break down, they release calcium back into the water, which ends up in the sand." That calcium gives out sand its brown color.

Compare that to the white, soft sands of tropical islands - they start as coral reefs. Sand at lakes and rivers is much darker than beach sand because it's high in silica from nearby mountains.

What they all have in common, though, is quartz, which is why sand sparkles. Even those tropical beaches have quartz even though it's not in their natural environment. The theory goes, said McElhatton, that birds stopping on the islands bring it over, and over time, have done so enough to give their beaches their glitter.

Sand, especially as dunes, is vital to protecting our Jersey Shore communities. Without it, the ocean would just eat away at the land. Annoying as it can be, thank the sand next time you're on the beach. It works hard for you.