( ( the mantle ) ( is ( ( ( the fold ) ( of skin ) ) ( that ( covers ( ( the ( vital organs ) ) ( that ( secretes ( ( the ( body armor ) ) ( called ( the shell ) ) ) ) ) ) ) ) ) ) )
(ROOT (S (NP (DT the) (NN mantle)) (VP (VBZ is) (NP (NP (DT the) (NN fold)) (PP (IN of) (NP (NN skin))) (SBAR (WHNP (WDT that)) (S (VP (VBZ covers) (NP (NP (DT the) (JJ vital) (NNS organs)) (SBAR (WHNP (WDT that)) (S (VP (VBZ secretes) (SBAR (S (NP (DT the) (NN body) (NN armor)) (VP (VBD called) (NP (DT the) (NN shell))))))))))))))))
the mantle is the fold of skin that covers the vital organs that secretes the body armor called the shell
(ROOT (S (NP (NNP Mantle)) (VP (VBZ is) (NP (NP (DT the) (NN layer)) (PP (IN of) (NP (NP (NN tissue)) (PP (IN between) (NP (DT the) (NN body) (CC and) (NN shell))))))) (. .)))