Following are a few organisms :

Lichens and Mosses.

Weathering by Living Organisms:

Living Organisms are cause biological weathering. Lichens growing on rock surface are able to extract minerals from the same. This produces small crevices where a thin layer of soil builds up. Mosses grow over these crevices. They cause deepening of crevices and building up of more soil in them. Deeper crevices form cracks.

The cracks become bigger when the roots of short lived herbs pass into them. With the passage of time roots of bigger plants pass into cracks. Cracks widen and cause slow fragmentation and later pulverisation of rocks.