These features result from the consolidation of sludge and slurry made up of tiny fragments, or spicules, of siliceous organisms such as the silicosponges . -- You needn't use 'so-called' since you're writing is directed to fellow scientists. Whetting with "coti" stones is particularly effective because they are very delicate and smooth, non-invasive or aggressive to the metal, and ensure great durability in the blade.
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