The near side of the rock has some long narrow stems that are more flat lying (a bit hard to see, but OK). The ones at the back do look like weathering pedestals, or hoodoo's, but maybe the stem is just buried inside. The grooves Andrew mentions are important, I think. In defense of Nasa's theory, there are concretions that shrink. Ones made of silica are initially gel like, and often shrink and crack. There are some phosphate ones in Utah like this too (named...variscites???). Hematite is usually a hard, crystaline material. Its crystals must be very small in these spheres. I don't see them. These are very unlike any hematite concretions of Earth, such as pisolites.

I saw an earlier sphere that clearly had a wrinkle - shrinkage texture on its surface.
If these were lifeforms, could some have been plump, and others starving. Or maybe they had an iron deficiency and membrane failure. The budding sphere, and triple berry, could these be buds? I have argued against this, because these fused spheres are quite rare. Perhaps these are a growth defect, instead, which would likely be rare. I am just casually speculating here, not making a real case.