Collecting seashells at the shore is a favorite summer pastime - but do you know what you're collecting?

"You could find up to 50 different kinds of shells on our region's beaches," said Amanda Lawless, a malacologist at The Academy of Natural Sciences of Drexel University. "There's probably more out there than what you'll find on the beach"

Rows of cabinets filled with shells from all over the world line the path to Lawless' office - the Academy is home to the second largest malacology collection in the country, the third largest in the world.

Water temperature is a factor in how much diversity shell seekers will find. "It's harder for any living thing to thrive in a colder environment, so you tend to find less diversity, fewer species where it's cold."

What you will find at area beaches is basically the makings of a nice seafood stew. "These three are all Atlantic surf clams," said Lawless, looking at a sample of seashells collected by The Pulse producers during a recent trip to Avalon, New Jersey.

Who killed the clam? 

One of the clams had a little hole on top, it looked like it had been drilled into the shell to be worn as jewelry. "The hole was made by a moon snail," explained Lawless. "These are predators who will come out of their shell and envelop the whole entire clam." Lawless said moon snails have rows of teeth that they rasp across the clam's shell.  "The moon snail secretes an acid that makes a hole into the shell, and then it inserts its mouth and eats the clam."

Several shells were tinted almost black - a few oysters and a scallop. "These have been buried deep in the sand when there is no oxygen, perhaps for hundreds of years," said Lawless. She said these blackened shells are washed ashore after big storms, or are dumped on the beach after dredging efforts.

The Pulse crew also found mussels (as in mussels marinara) and a jackknife clam, which is long and skinny. "They can grow past the size of your hand, and the animal inside is very long, and it fills up the whole inside," said Lawless. Jackknife clams bury themselves into the sand vertically. They are not usually eaten here, but are a very popular food in Asian countries.

Did you enjoy eating that knobbed whelk? 

Our last find was the most unusual one, said Lawless: a knobbed whelk, which looks a bit like a conch. The knobbed whelk is the state shell of New Jersey, but is not usually washed up on its beaches.

"This is a huge fishery, so people get excited when they find these on the beach, said Lawless.

"You wouldn't know that you are eating a whelk," she added, "they are often sold as conch fritters, or added into seafood stews." The creature inside the whelk looks like a garden snail, and is very big. "That's why they are such a popular item for fisheries, you get a lot of bang for your buck."