## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & & **New Mexico** & & & **Hawaii** & \\ \hline
**Cave** & **Four-Windows** & **Pantheon** & **A’a Cave** & **Maelstrom** & **Kula Kai** & **Tapa** \\ \hline
**Sample No.s** & **FW190831-01** & **BW180325-14** & **AA18113-05** & **MAL171220-11, -20** & **KK171218-6** & **TAP171219-3** \\ \hline
**Wt\%** & & & & & & \\ P2O5 & 0.30 & 0.31 & 0.17 & 0.24–0.26 & 0.25 & 0.23–0.25 \\ MnO & 0.18 & 0.18 & 0.17 & 0.17–0.18 & 0.174–0.18 & 0.17–0.18 \\ SO3 & 0.02 & 0.03 & 0.01 & 0.01–0.02 & 0.007–0.010 & 0.01–0.02 \\ FeO & 10.9820 & 11.34 & 10.350 & 10.6270 & 10.44–10.89 & 10.35–10.80 \\ \hline
**ppm** & & & & & & \\ Cu & 70 & 159 & 72 & 121–145 & 117–133 & 122–135 \\ V & 282 & na & na & 329 & 299–322 & 276–302 \\ \hline \end{tabular} Analyses by XRF at UNM; na = not analyzed.  
\end{table} 
Table 1: Concentration of selected elements and oxides in the basalt substrate, divided by cave. However, one of the larger anomalies encountered was that of Kula Kai Caverns. Kula Kai tended to group with New Mexico caves in alpha diversity analyses. Beta diversity also evidences Kula Kai overlapping with New Mexico cave distribution (Figure 3). One of the largest differences between Kula Kai and every other cave in our dataset is the fact that Kula Kai is a show cave, meaning that it is regularly visited by the public on cave tours. Not only is there a higher rate of human impact on the cave via tours, but there is also much more infrastructure above Kula Kai, increasing the potential for human impact. This includes a regularly traveled road, pit toilets, and housing. Additionally, Kula Kai is also at the highest elevation of all three Hawaiian caves, although they are less than a fifth of the elevation of El Malpais (Table S1). [PERSON] et al. [1] investigated the bacterial composition of Kula Kai using clone data and found the same distinction in community structure when compared to other Hawaiian caves. The four outliers from Kula Kai were a mineral crust, a microbial mat, moonmilk, and a coralloid sample. This, again, is probably best explained through an increased human impact on the cave. The samples that fell well within the range of Hawai i were two spheroids and an ooze sample. This makes sense as ooze is more prominently found in Hawai i and spheroids have not yet been discovered in lava caves in El Malpais. A large part of the existing literature on cave microbes has focused on microbial mats and other cave features, not discussed here [29; 64; 66]. This study is one of the few to look at multiple and various speleothems across lava caves in Hawai i and New Mexico. There appears to be differentiation in the microbial composition of speleothems (Figure 4). While most of the speleothems divide out separately from one another, mineral crusts seem to cover the entire gamut of microbial communities found in speleothems. We believe that this might be evidence of the fact that mineral crusts, in caves, will eventually overrun most other speleothems. One of the only speleothems that does not appear to have overlap, both visually in situ and in our NMDS plots, are spheroids. However, it is worth noting that the only spheroids that were found were found in Hawai i. Additionally, it has the lowest number of samples collected (n = 3), preventing the estimation of an ellipse in beta diversity. However, when placed into an NMDS, spheroids group clearly with the Hawaiian samples (Figures 3 and 4). This makes sense, as spheroids are composed of gypsum, which is rare in the other speleothems, and spheroids have not yet been found in New Mexican lava caves. Our suite of secondary morphologies could provide the foundation for viable biosignatures on other planets. [PERSON] [64] suggests that viable biosignatures must be uniquely discernable at both the macroscopic and microscopic levels, identifiable via non-visual inspection, and must be \"...relatively independent of the specific life chemistries of the responsible microorganisms\".