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I haven't the foggiest idea what this is. UV-fluorescent organism, or non-organism, or leavings of an organism...?... found on the W-facing side of a cinder block wall, noticed due to high fluorescence, while I was using a UV flashlight to hunt lichens. Thing is attached to the mortar between bricks. I would remove the thing to dissect and investigate further, but I'm not sure this isn't some kind of extraterrestrial life that will kill me if I handle it too much (99% joking there). What the hell is this thing? Texture rather hard, and crispy, not fleshy. Observed following a decent amount of precipitation on the same day.

Photos # 1-3 taken under UV light in near total darkness otherwise, and photos # 4-5 taken under illumination with a white LED lamp. Coin used for scale is a US quarter dollar (¢25 piece), 24.26 mm, 0.955 inch in diameter. Each line on the edge of the coin is approximately 0.64 mm apart.

Update (29 Dec 2022): Inspected the putative life-form further, and removed the donut-shaped structure from the large mass, and the larger mass from the wall. The donut-shaped structure was relatively easy to separate, as was the larger mass from the wall. Face, and backside fluorescent under UV, as well as the inside of the larger mass (not pictured under UV here). The donut-shaped structure was hardened, and fragile, and shattered into pieces when I accidentally dropped it on a tile floor.