 It is common for freshwater crabs to have large eggs, and this is also seen in "Seychellum"; its eggs are around in diameter, which Rathbun described as "very large".Adult specimens reach a carapace width of , and a carapace length about 80% of the width.The carapace is almost quadrangular and quite flat, in constract to the more rounded outline in its closest relative, "Deckenia".