Worn out 3 tab in need of replacement

this causes shingles to wear out prematurely and to wick moisture under the shingles causing nails to rust 

Moss feeds off the moisture and the shingles. Causing them to break down, the granules to fall off and the nails to rust from all the moisture between the shingles 

As you can see the siding is too close to the shingles causing the wood siding to wick up moisture into the siding causing it to rot and mold.

      Lots of moss, lichen, algae, and mold growing everywhere around the 2 dormers

You can see im holding 4 layers of shingles each layer has 1 starter shingle and 1 main shingle. With a total of 4 layers of shingles. 2 for each layer