C. solida may refer to:

• Archips solidus, a species of moth, synonymized as Cacoecia solida Meyrick, 1908
• Cellana solida, a species of sea snail
• Clathrodrillia solida, the solid drillia, a species of sea snail
• Clavaria fragilis, fairy fingers, a fungus synonymized as Clavaria solida Gray, 1821
• Coelolepis solida, an extinct species of jawless fish
• Corydalis solida, the fumewort, a flowering plant of northern Eurasia
• Crepidula adunca, a species of sea snail, synonymized as Crepidula solida Hinds, 1845
• Eucithara solida, a species of sea snail, synonymized as Cytharopsis solida (Reeve, 1846)