## 4 Discussion
While we were limited in our investigation, our proposed biosignatures meet many of the established criteria. All of our biosignatures are distinctly identifiable at the macroscopic level. However, it is less clear at the microscopic level, but our results suggest that some of these speleothems are, in fact, identifiable via their microscopic appearance. It is worth noting, however, that these SEM micrographs only represent a few samples across both locations, and therefore these conclusions are not definitive. Instead, they point in a direction that suggests uniqueness, although further studies should be conducted to confirm the veracity of such claims at the microscopic level. Spheroids are unique and easily noticeable by the unaided eye but are also distinctive at the microscopic level. Microscopically and macroscopically, spheroids have distinctive ridges in them that are both microscopically identifiable and unique under the SEM. Additionally, spheroids are composed of gypsum, another unique marker. Spheroids are also strong candidates as biosignatures, as they are seemingly unique in their microbial community composition too, although that must also come with the caveat that we only analyzed three spheroids at the molecular level, which might account for such drastic differences. Moonmilk is identifiable to the unaided eye, and its appearance can be confirmed by its unique morphologies under the microscope. Calcitic moonmilk, both crusty and fluffy, contains filamentous and crystalline calcite [52]. Both the physical appearance of moonmilk under the microscope and the EDS spectra unique to calcite help to make this a good biosignature in lava caves on Mars. Ooze is also a viable option, as it is identifiable at the macroscopic level as well as the microscopic. At the level of the SEM, ooze looks like an amalgam of different organic and inorganic materials. EDS spectra confirm this through aluminum, silicon, oxygen, carbon, and calcium peaks. The organic signatures, as well as a visual inspection with the microscope, reveal that ooze is, or was, teeming with life. The final three were more difficult to distinguish at the level of the electron microscope. Coralloid surfaces tended to alternate between smooth areas and areas of \"flaky\" minerals, or what looks like detritus. Additionally, they tend to be composed of both silica and minor calcite composition [27]. Distinguishing between a mineral crust and a microbial mat at the macroscopic level is easy, while microscopically, it is dependent on the amount of life found at the sample's surface. Microbial mats have considerably larger areas of colonies, observable at the surface, compared to mineral crusts. Occasionally, mineral crusts will be associated with a unique sample surface chemistry, detectable through EDS, but this is not always the case. Such an example is that of blue-green mineral crusts that have been observed in both Hawai' i and New Mexico, which generally also have either a copper peak in the spectra, bismuth, or vanadium. While this analysis of the SEM is by no means exhaustive, it does suggest that further research on all six of our potential biosignatures is warranted. We discovered that both species richness and overall library sizes were significantly greater in caves in Hawai' i than in New Mexico. Abiotic factors that appear to contribute to this difference include elevation, as New Mexico's elevation is more than five times higher than that of our Hawaiian caves. Additionally, precipitation in Hawai' i is considerably higher, on average, and surface and cave temperatures also are considerably higher in Hawai' i. There are a greater number of microbial bacterial groups that are predominantly found in New Mexico rather than Hawai' i. These include _Blastocatella, Bryobacter, Candidatus_ Udaebacter, _Pseudonocardiia, Rubrobacter, Solirubrobacter_, unclassified (family Solirubrobacteraceae), unclassified (family 67-14), and unclassified (family Microcaceae). _Blastocatella_ is a genus within subdivision 4 of the Acidobacteria.