( They ( ( have ( ( ( a ( special ( bony ( or ( cartilaginous shell ) ) ) ) ) ( developed ( from ( their ribs ) ) ) ) ( that ( acts ( as ( a shield ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP have) (NP (NP (DT a) (JJ special) (NN bony) (CC or) (NNS cartilaginous) (NN shell)) (VP (VBN developed) (PP (IN from) (NP (PRP$ their) (NNS ribs)))) (SBAR (WHNP (WDT that)) (S (VP (VBZ acts) (PP (IN as) (NP (DT a) (NN shield)))))))) (. .)))
They have a special bony or cartilaginous shell developed from their ribs that acts as a shield.
(ROOT (S (NP (JJS Most) (NN turtle) (NNS bodies)) (VP (VBP are) (VP (VBN covered) (PP (IN by) (NP (NP (DT a) (JJ special) (NN bony) (CC or) (NNS cartilaginous) (NN shell)) (VP (VBN developed) (PP (IN from) (NP (PRP$ their) (NNS ribs)))))))) (. .)))