Among the Dead Sea scrolls, 7Q5 is the designation for a small papyrus fragment discovered in Qumran Cave 7. The significance of this fragment is derived from an argument made by Spanish papyrologist Jose O´Callaghan in his work ¿Papiros neotestamentarios en la cueva 7 de Qumrân? ("New Testament Papyri in Cave 7 at Qumran?") in 1972, later reasserted and expanded by German scholar Carsten Peter Thiede in his work The Earliest Gospel Manuscript? in 1982. The assertion is that the previously unidentified 7Q5 is actually a fragment of the Gospel of Mark, chapter 6 verse 52-53. The majority of scholars have not been convinced by O'Callaghan's and Thiede's identification and it is "now virtually universally rejected".
Read more about 7Q5: O'Callaghan's Proposed Identification, Argument, Significance