Why So Many Black Seashells?

lettered olive with other seashells

Seashells come in many lovely colors, but it’s odd to find all black seashells. Certain shells have dark lines or spots and are made that way by the snail inside, but this is different. One day while collecting shells, I found an unusual number of all-black shells.

Sometimes out in the wild a living shell, or shell still under the water, will be covered in a dark, sometimes fuzzy, coating. That is the periostracum, or skin, which creates an outer layer over the shell. I have a horse conch which I cleaned, but never removed all that layer. The shell underneath was still light colored.

But some shells, like these Jingle shells, are all black.   They may have begun as some pretty orange or white color, but have turned black due to the sediment where they were buried. It has to do with sulfur content in the sand, or something. I am no scientist, so I won’t try to explain the process – I would just confuse myself and you! My message here is that they don’t begin black.
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These jingle shells were collected near Ponce Inlet on the East coast of Florida.  You can see that one of them (in the photo above) is just beginning to turn from it’s light orange color.  It may not have been buried as long as the others.  Constant wave action is bound to unearth shells and eventually wash them ashore.

Below, I have worn oyster shells and piece of something that was probably a whelk among the ridged jingle shells.
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The partial whelk shell below has also turned black.  These shells do not start out this way.  Whelks are generally tan with brown stripes or light in color.  The one in my photo below is probably either a Lightning Whelk or Knobbed Whelk.  It’s too broken for me to tell.

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Shells are often not pretty when found. Especially if they are found in the water. They can be dark or coated with green, with barnacles or oysters attached. Shells found up on the sand can be white, or much lighter in color that they were when inhabited. The sun can bleach them. This makes seashell identification harder. It can be just as difficult when collecting shells that have turned totally black.


Fiddler crab

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cockle shells underside

Collecting Seashells: Grouping the Bivalves

The bivalve seashells, or shells that come in two parts or halves, can be similar in appearance, but not all bivalves are “clams”. I’m not scientifically minded, but I’ve been learning the difference between the shells I collect and photograph. I’ve gathered some photos of the more common bivalves I see on beaches and in […]

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collection of calico scallop shells

Scallop Shells Collected on the East Coast

While photographing my newly collected shells the other day, I decided to re-photograph my pretty scallop shells. Florida waters can contain a variety of types of scallops, but the shells I find over here on the east coast are mainly the Atlantic Calico Scallop. While beachcombing in my area of Florida, the best shells are […]

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23 thoughts on “Why So Many Black Seashells?

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  9. charlie

    while in North Carolina walking Kurie Beach looking to bring my wife home a treasure I fond a beautiful black conch shell! I cant find anything like it anywhere on the web . Your site is the closest yet. Someone on line said they are worth tens of thousands of dollars! Thoughts

    1. Pam

      I’ve never heard that black conchs are worth a lot of money, but I have no idea really. Asking a knowledgable seashell collector would give you the best answer. I’ve always thought that for shells to be worth anything they had to be rare and in perfect condition. Black shells have usually been buried and have lost their original coloring. If you ever find more information, I’d love to hear.

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  12. karen

    I found many black whelck conch shells on the coast of North Carolina. I was giving them away on a ferry and people told me they were very old. Is this true?

    1. Dustytoes

      Hi Karen, they probably are old but I don’t know how “old”. It takes a while for shells to turn black from being buried in certain types of sand for a long time. I don’t know how long it takes for them to turn black.

    2. shirley davis

      these shells have been buried in a sediment in the water so i guess it would be ols having to sit in the sediment for a long time

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  15. Becki Yawn

    I was at Murrell’s Inlet, SC last week and saw many black shells, scallops, oysters, whelks, cockles, etc. It seemed very odd to me. Since this was the week on the total eclipse, I started calling them “eclipse” shells. I was searching the web to see why they were black when I found your blog. I have collected shells from many of our American beaches, throughout FL, AL, GA, SC, TX, LA, CA over the last 50 plus years. I have never seen so many at one time.

    1. Dustytoes

      Maybe all those black shells were unearthed by a storm? I like your choice of naming them “eclipse shells”. You must have a nice collection from your travels. I would love to travel to, and do some shelling, on the South Carolina coast. Thanks for sharing!

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