The objects in the photo are land snail shells. Minnesota is home to many species of minute terrestrial snails but they are little studied and their life histories aren't well known. So far as we know these tiny mollusks don't harm anything of importance to people. They are found most often in moist places rich in organic matter such as woodland soil and duff. We don't know why the shells ended up on the wall.

The following is somewhat technical, but it may be of interest:

http://www.dnr.illinois.gov/conservation/iwap/documents/swgreports/t-32-p-1_final-survey%20of%20land%20snail%20diversity%20across%20multiple%20habitat%20types%20in%20sothrn%20il.pdf