Sentence:  Inside , carefully packed in straw , were six eggs , but the eye of a poultry psychologist was required to detect what scientifically valuable specimentalia lay inside ; to Alex they <WSD>were</WSD> merely six not unusual hens ' eggs . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)