 Hmmm, might be an abalone shell.
( Hmmm ( , ( ( might ( be ( an ( abalone shell ) ) ) ) . ) ) )
(ROOT (S (ADVP (RB Hmmm)) (, ,) (VP (MD might) (VP (VB be) (NP (DT an) (JJ abalone) (NN shell)))) (. .)))
I have read a book that described an abalone shell.
( I ( ( have ( read ( ( a book ) ( that ( described ( an ( abalone shell ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP I)) (VP (VBP have) (VP (VBN read) (NP (NP (DT a) (NN book)) (SBAR (WHNP (WDT that)) (S (VP (VBD described) (NP (DT an) (JJ abalone) (NN shell)))))))) (. .)))