Seashells by Millhill

Sea Biscuits On Sanibel Island?

Sea biscuit sand dollar — Large Sea Biscuit

I recently had a reader ask me if the treasure she found along the beaches of Sanibel, Florida was a Sea Biscuit. I have a couple of sea biscuits, which are puffy sand dollars, but I didn’t find my large one, I bought it at a shop years ago. I may have found the small one, but don’t remember.

Anyway I really don’t know much about the sea biscuit so I checked with my favorite shell blogger, Pam at the “i love shelling” blog and she had one page, with lots of cool photos, of many things, but no sea biscuits. Pam lives there and goes shelling most every day (how lucky is that?) and she also mentions that she hasn’t found any Sea Biscuits on Sanibel. According to her they are found in the upper Florida Keys.

She does have photos of “potato” or “heart” urchins on the beach.
You can visit that page here.

Do you have any info to add about the Sea Biscuit sand dollar? Leave a comment to help us out please!

For more on Sand Dollars:
The Sand Dollar

Visit Pam’s wonderful blog about shelling on Sanibel Island:
i love shelling

Tiny Coquina Shells Used to Build a Fort

Coquina shells are tiny and numerous and can be seen all along the Florida coastline. These are the tiny shells you may see quickly digging into the sand as the surf receded from the beach. The beach seemingly comes alive as the tiny Coquina quickly cover themselves over and over. The sea birds eat them, and it looks to me like the shells are in a constant game of hide and seek – for their life!

It’s quite amazing that these little shells, when grouped together, make up a material which is hard enough to be used to build a structure, much less a huge fort! But that is what the historical Castillo de San Marcos fort in St. Augustine, Florida was made from. Yes, the basic material for those big walls is tiny seashells!

castillo de san marcos fort — Inside the Castillo de San Marcos Fort in St. Augustine, Florida

The Wandering Meatloaf Seashell

Have you ever looked down and seen a giant, 13 inch brown thing moving through the water? Sounds a bit nasty doesn’t it? Think a slab of mom’s meatloaf with dents in it. Actually the common name of this shell would be “Gumboot chiton” and it was named for it’s appearance to the rubber sole of boots. The Wikipedia page (link above) says that some people refer to it as the “wandering meatloaf” and looking at this photo, I can see why. It is actually a giant Pacific chiton – pronounced “kite -n” or see here.

Chitons are of the class, Polyplacophora and their common name is “sea cradle”. They are composed of eight plates that overlap one another to cover their topside. These are held in place by a girdle that surrounds them, or in some cases, like the gumboot chiton, the girdle covers the plates.

Chitons are odd looking and not at all what I think of when I hear the word seashell, but the animal lives only in ocean water but can be found in cold as well as tropical seas. It attaches itself to rocks and can be found on top of them or under them. It’s hard shell plates protect the top, but it can roll into a ball, if it has to, for more complete protection.

Although the Gumboot is the largest at 13-14 inches (33 plus cm), chitons can also be less than an inch long and not all of them are brown like a meatloaf. The White Northern Chiton is light colored and the Rough-girdled Chiton has spiky hairs along the girdle.

An interesting note about chiton shells is that the plates will come apart once the animal has died and when they wash up on shore you may wonder just what it is you’ve found. The shape of the plates have caused them to sometimes be called “butterfly shells”. Scroll down the page and see some here.

The book I own and use for reference is the National Audubon Society Field Guide to Shells.

Identify more of your shells at Seashell Identification.