'Mermaid's necklaces' wash up on shores at Outer Banks

'Tis the season for "mermaid's necklaces," according to Cape Hatteras National Seashore officials. 

The long casings that come from whelks--a type of sea snail--wash up on the shores of beaches on the coast of the Atlantic from Massachusettes to Florida, according to the Smithsonian Marine Station.

The whelk's reproductive season begins in March and lasts through September. Female whelks will lay a string of eggs in deep water twice a year. Babies hatch anywhere from three to 13 months after that.

According to the Cape Hatteras National Seashore officials, the whelk egg casing, which some people also call "fisherman's soap," can house 20 to 100 eggs in a pouch, and a string usually consists of up to 40 pouches. On average, the casings are about three feet long.

So look down if you're walking along the beach this Fall. You never know what you might find!