The creatures found by the polar expedition appear to be an unknown hybrid of plant and animal tissues. Paleontological examination found no matching ancestors in the fossil record. Zoological research found no descendants amongst living species. Chemical analysis of the frozen tissues provided the most revealing results.
The chemical makeup of the creatures' body tissues were in proportions not found in any known plant or animal found on our world. Moreover several rare chemicals, including some previously unknown compositions, were abundant in the creatures' bodies. Whatever air they had breathed, whatever food or drink they had consumed, it had not originated on our world. The conclusion of the investigating team was that these creatures must have come from somewhere beyond our planet.
Additional conclusions of the investigating team: The creatures were very likely intelligent - note the ratio of brain size to body mass. The creatures were almost certainly engineered - The hybridization of plant and animal tissue is body-wide, however each tissue type is discrete apart from a blending membrane of scar tissue, indicating that the hyrbridization was performed as a grafting process.
Follow-up note: Two weeks after the examination ended, one of our laboratory techs committed suicide. During the subsequent investigation, it was determined that many of our technicians had been suffering from disturbing dreams after having contact with the creatures. For the most part, these dreams ended shortly after the autopsies were concluded, however there may a connection to the suicide, as the tech was considered a highly sympathetic and 'sensitive' individual.
You may find the attached pre-autopsy image of one of the creatures disturbing. If you should experience headaches, nausea or strange dreams, please contact medical personnel immediately. Refer them to the security code below.