that 引起的是一个定语从句(the researcher claimed were from a previous experiment),这个定语从句中,主语the researcher, 谓语 claimed, 关系代词that 代替a pile of pens 作claimed后面宾语从句的主语,were是宾语从句的系动词谓语,from a previous experiment是介词短语作表语。为了便于你理解,我把这个定语从句改写成:The researcher claimed a pile of pens were from a previous experiment.