The shell of the periwinkle (Rapana venosa) is a valuable by-product and can be used for commercial, decorative, and industrial purposes. Never throw the shells away after processing the snail meat—if handled correctly, they can be turned into substantial income-generating products.


 Below I list the most used and profitable evaluation areas:


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 🟩 1. Crushed Shell – Source of Calcium (CaCO₃)


 Black Sea snail shells contain 85–97% calcium carbonate (CaCO₃), making them a valuable raw material.


 ✔ Areas of Use
 • Chicken feed additive (increases egg shell hardness)
 • Fish feed production (especially in sea bass and sea bream farms)
 • Agricultural soil pH regulator (replaces lime)
 • Organic fertilizer production


 ⚠ Advantage: It has a higher CaCO₃ ratio than crab/crayfish shells; it is a very high quality mineral source.


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 🟩 2. Aquarium and Ornamental Products


 Boiled and cleaned shells:
 • Aquarium decor
 • Terrarium decor
 • Home decorative items
 • Magnet, keychain, night light designs


 Even in tourist areas, they can be sold for 10-25 TL per piece.


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 🟩 3. Garden and Landscape Materials


 Broken shells:
 • Drainage material in flower pots
 • Ground cover in the landscape (lawn edge, road edge)
 • pH regulator in soil


 Crushed seashells are sold at very high prices in the landscaping industry abroad (20–40 USD / 20 kg bag).


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 🟩 4. Handicraft – Jewelry and Figurine Production


 It can be made from shells of suitable size:
 • Necklace, earrings, bracelet
 • Small figurine, ornamental bowl
 • Candle holders, small decorative objects


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 🟩 5. High Value Added Product: Calcium Powder / Nano-Calcium


 Income can be increased by finely grinding the shell and selling it as CaCO₃ powder.
 Its industrial value is high in the plastic, paint, ceramic and paper industries.


 If you have a grinding machine → very profitable product.


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 🟩 6. React the Peel with Vinegar/Lime to Create a Top Quality Calcium Solution


 By reacting the peel with a weak acid (e.g. apple cider vinegar):
 • Liquid calcium fertilizer
 • Plant food
 • Organic calcium additive


 You can produce.


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 🟩 7. Terrazzo / Mosaic Floor and Countertop Production


 Broken shells:
 • Terrazzo style ornamental panels mixed with epoxy resin
 • Table surfaces
 • Stand
 • Decorative wall panels


 can be used in construction.


 It is sold at very high prices in tourist areas.


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 🟩 8. Welding Beads – Building Material


 Shells as a source of calcium:
 • Cement additive
 • Ceramic clay
 • Lime production
 • Road embankment


 can be used as.


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 🟦 9. Mineral Premix for Animal Feed


 When micronized:
 • Chicken
 • Turkey
 • Cattle-sheep
 • Fish food


 It is added to mineral mixtures for