Glacial erratic boulders of the Ostseekalk type, late Caradoc in age, contain spumellarian radiolarians with their skeleton substituted by iron minerals secondarily oxidized to goethite. Species of both the Inaniguttidae, characterized by the presence of a small spherical central shell, and Entactiniidae, with a transverse central bar, have been identified. A similar radiolarian assemblage, but with original siliceous skeletons preserved, has been identified in a graptolitic lirnestone boulder, early Ludlow in age.
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