there are several well known cases in the field of ufology which involve 'landed' ufos.
these are interesting because skeptics cant use the 'misidentification of astronomical bodies' argument.
one such case that has intrigued me for years, is that of stefan micholak.
micholak claimed that he saw 2 cigar shaped objects hovering in the air then one of these objects actually landed. whatever this object was left physical traces at the landing site proving that something had actually landed.
michalak claimed that a 'door' had opened in the side of the craft and he could see inside. after some time, the door closed and the craft began to rotate counter clockwise. at this point, the craft exuded a gaseous substance from a vent that michalak had noticed on the side of the craft. this set his clothes on fire and caused him to jump back. the craft then rose to about 40 feet in the air and subsequently vanished.
michalak soon felt extremely nauseous and confused. he managed to find his way home (taking some 9 hours to do so) and over the next several weeks became very ill.
the burn marks on his abdomen were in the exact shape of the vent that he described on the side of the craft, and curiously, these burn marks re-appeared every 3 months over aperiod of about 14 months. doctors had no explanation for whatever was causing this.
ps. i havent been able to find any debunking of this case at all. i would appreciate it if anyone has any references to this case from any skeptical publications.