On the head of the epididymis is a small stalked appendage (sometimes duplicated). It is named the appendix of the epididymis (or pedunculated hydatid), and is usually regarded as a detached efferent duct. This structure is derived from the Wolffian duct as opposed to the appendix testis which is derived from the mullerian duct remnant. [ http://en.wikipedia.org/wiki/Appendix_of_epididymidis ]