Issued by Spanish Guinea in 1954 to commemorate Día del Sello Colonial (Colonial Stamp Day), this striking semi-postal stamp features a gracefully swimming sea turtle above coral formations. The 5+5 cts denomination indicates a postal value plus a surcharge, typically used for charitable or promotional purposes. Printed in a bold monochrome red tone, the design reflects both marine biodiversity and colonial-era philatelic themes. The inscription “Guinea Española Correos” highlights its origin under Spanish administration. This issue is particularly appealing to collectors of marine life, colonial territories, and semi-postal stamps. Its clean layout and symbolic subject make it a standout addition to thematic collections.