Coralline algae (Rhodophyta, Florideophyceae) are one of the most abundant organisms in the hard-bottom marine photic zone where they provide settlement substrates, structure and shelter on rocky substrates. Coralline algae also play important roles in tropical reefs, both cementing corals together and producing substantial amounts of calcium carbonate. The ecological roles of coralline algae in the marine environment are related to the biomineralization process that occurs in the cell walls. Currently, this group of algae is receiving renewed attention from researchers from different fields, especially due to possible effects of climate changes over its magnesium calcite skeleton. Despite this renewed attention, we still have poor information regarding the first steps of coralline algae ontogeny and calcification. The aim of this study was to describe the earlier steps of Lithophyllum corallinae development and its calcification process. Algae were collected at Vermelha Beach, Rio de Janeiro city. Adult crusts released spores that settled over microscope slides. The germinating spores were analyzed by Polarizing Light Microscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Transmission Electron Microscopy and Atomic Force Microscopy. Results showed that cell walls mineralization begins at third spore cell division (8 cells specimen), evidenced by changes in light polarization, elemental composition and hardness, restricted to the cell walls of the innermost part of the developing spore. Nanopores in calcite crystals structure were identified, evidencing macromolecules occlusion, a feature especially important to prevent calcite skeleton cracking in high-energy environments. The beginning of this process could be related to spore size, availability of organic matrix and energy from photosynthesis. All the analysis also confirmed the lack of calcification in the cell walls of the outermost part of the germinating spore, which allows the growth of the individual; but mainly indicates a high level of control in coralline algae mineralization process, representing a relevant information in future studies on coralline algae calcification, including those testing climate changes scenarios.

珊瑚藻 (Rhodophyta, Florideophyceae) 是硬底海洋光区中最丰富的生物之一，它们在岩石基质上提供沉降基质、结构和庇护所。珊瑚藻在热带珊瑚礁中也发挥着重要作用，既能将珊瑚粘合在一起，又能产生大量的碳酸钙。珊瑚藻在海洋环境中的生态作用与细胞壁中发生的生物矿化过程有关。目前，这组藻类正在重新受到不同领域研究人员的关注，特别是由于气候变化可能对其镁方解石骨架产生影响。尽管引起了这种新的关注，但我们仍然对珊瑚藻个体发育和钙化的第一步知之甚少。石竹发育及其钙化过程。藻类是在里约热内卢市的 Vermelha 海滩收集的。成虫结痂释放出落在显微镜载玻片上的孢子。通过偏振光显微镜、扫描电子显微镜、能量色散光谱、透射电子显微镜和原子力显微镜分析发芽孢子。结果表明，细胞壁矿化始于第三次孢子细胞分裂（8 个细胞标本），光偏振、元素组成和硬度的变化证明了这一点，仅限于发育中孢子最内部的细胞壁。方解石晶体结构中的纳米孔被鉴定，证明大分子闭塞，这是防止高能环境中方解石骨架开裂的一个特别重要的特征。这一过程的开始可能与孢子大小、有机基质的可用性和光合作用产生的能量有关。所有的分析还证实了发芽孢子最外层的细胞壁没有钙化，这使得个体能够生长；但主要表明对珊瑚藻矿化过程的高度控制，代表了未来珊瑚藻钙化研究的相关信息，包括那些测试气候变化情景的研究。