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Reconstruction of the living Namacalathus. 1, stem; 2, parental cup; 3, daughter cups; 4, hollow ciliated tentacles; 5, spines; 6, lateral lumen; 7 central opening; 8, inner skeletal layer—foliated with columnar microlamellar inflections; 9, internal (middle) skeletal later—organic rich; 10, external outer skeletal layer—foliated with columnar skeletal inflections (image copyright: J. Sibbick).
