NOT A TEACHER.
I don't know the original sentence where you take this "were found" from, but I think it's a passive sentence with past tense. Your sentence might have the structure like this: S (plural noun/you) + were found + (somewhere)... My tip for you is wherever you see "be" followed by a part participate form of verb, think of passive voice first.
Of course it's totally different from past perfect tense, because the structure of this tense is: S + had + past participate
Hope you find this useful!
- For Teachers