( ( ( About ( seven years ) ) ago ) ( , ( ( marine scientists ) ( ( discovered ( that ( there ( ( ( ( are ( ( ( ( ( between 10 ) and ) 50 ) million ) viruses ) ) ( in ( ( every milliliter ) ( of seawater ) ) ) ) , ) ( making ( ( marine viruses ) ( ( the ( ( most abundant ) organisms ) ) ( on earth ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (NP (RB About) (CD seven) (NNS years)) (RB ago)) (, ,) (NP (JJ marine) (NNS scientists)) (VP (VBD discovered) (SBAR (IN that) (S (NP (EX there)) (VP (VBP are) (NP (QP (IN between) (CD 10) (CC and) (CD 50) (CD million)) (NNS viruses)) (PP (IN in) (NP (NP (DT every) (NN milliliter)) (PP (IN of) (NP (NN seawater))))) (, ,) (VP (VBG making) (S (NP (JJ marine) (NNS viruses)) (NP (NP (DT the) (ADJP (RBS most) (JJ abundant)) (NNS organisms)) (PP (IN on) (NP (NN earth)))))))))) (. .)))
About seven years ago, marine scientists discovered that there are between 10 and 50 million viruses in every milliliter of seawater, making marine viruses the most abundant organisms on earth.
(ROOT (S (NP (NNS Viruses)) (VP (VBP are) (NP (NP (DT the) (ADJP (RBS most) (JJ abundant)) (NN type)) (PP (IN of) (NP (NP (JJ biological) (NN entity)) (PP (IN on) (NP (DT the) (NN earth))))))) (. .)))