( ( Gems ( and ( metal ores ) ) ) ( ( are ( ( their foods ) ( of choice ) ) ) . ) )
(ROOT (S (NP (NNS Gems) (CC and) (NN metal) (NNS ores)) (VP (VBP are) (NP (NP (PRP$ their) (NNS foods)) (PP (IN of) (NP (NN choice))))) (. .)))
Gems and metal ores are their foods of choice.
(ROOT (S (NP (NNS Metals)) (VP (VBP start) (PRT (RP out)) (PP (IN as) (NP (NN ore)))) (. .)))
Metals start out as ore.