number of embedded spherules (in the plain's sediments) is probably much higher than the number of loose spherules (on soils). Since (1) the estimates of the erosion depth of original sediment needed to produce the loose spherules are less than 1 meter, while (2) the typical depths of the plain's sediments are several hundred meters. Shiny Blueberries without Dust The image at right (Figure 14) shows shiny hematite blueberries. The shininess and the position of these blueberries are unusual. The rover Opportunity dug a trench into the top soils that lie over the Meridiani Planum's sediments. Figure 14 shows a wall to the newly dug trench with (partially uncovered) soil-embedded blueberries. Soil-embedded blueberries are rare. Size-sorting tends to position loose blueberries on or very near the surface of soil bedforms. Almost all photographed blueberries were exposed to the atmosphere and are now covered in a layer of Mars's dust. The layers of dust take away the shininess of the blueberries. The blueberries inside the trench are dust-free because the interiors of soil beds are largely dust-free. Without the dust, these blueberries are shiny. Blueberries on Earth Earth analogs Researchers from the University of Utah have explored the similarities between the blueberries and spherical concretions discovered within "Jurassic Navajo Sandstone" in southern Utah. They have concluded Mars must have had previous ground water activity to form the blueberries. However, they do note the spherules are more spherical in the Martian sample due to the lack of "joints, fractures, faults, or other preferential fluid paths", unlike the Utah sample. A team of researchers from Japan studied the spherules found in Utah as well as spherules that were later discovered in Mongolia, in the Gobi. They found evidence that the concretions found in these locations are first formed as "spherical calcite concretions" in sandstone. Acidic water rich in iron then dissolve the calcite leaving behind the iron rich (hematite) spherule. This leads to the conclusion that the blueberries may have formed early in Mars's history when the atmosphere was more dense by the same process. Hematite spherules used to support pseudoscience clickbait In 2021, a predatory journal Advances in Microbiology'' published a paper ( ) that made a bogus claim using photos of Martian hematite spherules. Biologist PZ Myers dismissed the paper as "an extraordinary claim that requires better evidence", noting that the paper's first author had previously concluded from similar photographic analysis