What We Do Citizen Science Great Eggcase Hunt British Isles & NW Europe THORNBACK RAY (Raja clavata) Size:Maximum Eggcase Length: ~12cm (ranges from 10–15cm)Eggcase Length (without horns): ~6.5cm (ranges from 5-8cm)Maximum Eggcase Width (with keels): ~4cm (ranges from 3–7cm)Range: The Thornback Ray has a widespread distribution across the Eastern Atlantic from Iceland to South Africa, including the North Sea, western Baltic Sea, Mediterranean Sea and Black Sea. Similar Eggcase: The larger Blonde Ray eggcase. The smaller and textured Starry Skate. And the Small-eyed Ray which has narrower upper horns and shorter lower horns. Great Eggcase Hunt Records: Thornback Ray eggcases are commonly reported and have been submitted from the majority of the British coastline.