This formation was found in the Capital Reef area of Southern Utah (38.2970546, -111.2979319).

There wasn't just one, but several of these small crater formations all over the area. All of them had the same basic structure: a ring of raised rock with fins, surrounding a depression that seems to be at about the same level as the surrounding rock. The rings were darker in color with lighter fins, and the depressions in the middle are lighter in color. All about 20-40 cm in diameter. The rock they are in is most likely a sandstone.

Does anybody know what this is and how it was formed?

The first image is a nearly straight down view, and the second image is an angled image to highlight the fins that ring the depression.

Keys for scale (there wasn't a banana available ;) )

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  • $\begingroup$ Just FYI be careful photographing keys in the future people can actually make copies of keys from photos now, Coins work nice since they are standardized. $\endgroup$ – John Apr 12 '18 at 22:39
  • $\begingroup$ While I agree that one should be careful with photographing keys, if someone wants to take the time to track me down, make a copy of my keys, and steal my car... then they absolutely deserve to go to jail. $\endgroup$ – Benjam Apr 15 '18 at 4:38
  • $\begingroup$ @Benjam: Also, if your car is relatively new (last 15-20 years), the key probably has an embedded electronic transponder chip, so even if you cut a copy of the key, it won't work unless you also get the chip programmed. $\endgroup$ – jamesqf Apr 15 '18 at 5:01

Relief features made by microbial mats which were gelatinous. The ridges and fins are thought to be caused by small currents that flowed through the umbrella like bodies of these ancient bacteria.

  • $\begingroup$ So were these microbial mats around when the surface was first deposited? Or did they come after? It seems like they may have come after, because there were more than a few of them around. And it seems unlikely that they all would have been uncovered. But I'm not sure, hence the question. $\endgroup$ – Benjam Apr 15 '18 at 4:45

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