Hi,

With that body form and the long hairs on its body, that might looks like an astigmatid mite (Order: Astigmata) in the genus Glycyphagus or the genus Tyrophagus.
Here are examples of what those types of mites look like for comparison....
https://bugguide.net/node/view/1315938
https://bugguide.net/node/view/875650/bgimage

These types of mites can be found in a variety of situations indoors or out. They thrive in damp/moist areas where they feed primarily on molds. Indoors, they are often associated
with stored grain or other stored food products, but they can occasionally attack and damage greenhouse-grown vegetables or ornamental plants. They don't form webbing like spider mites do, so I don't think they are coming from the cotton-candy-like webby mass on your string of pearls plant. They might not be responsible for the leaf discoloration on your corn plant either, since these mites did not show up until after that damage occurred.

Two control measures could help reduce the numbers of these mites or eliminate them. First, if there are stored foods that seem to be infested with these mites, eliminate that material. Secondly, these mites desiccate if the humidity is low, so anything that can be done to eliminate water leaks, decrease condensation on windows or other cool surfaces, increase ventilation, or otherwise decrease humidity should help. I don’t think other control measures would be needed, but if they are, you could consult a licensed pest control company.

Hope that helps!