(New for school year 2015-2016)
This video shows a series of (logarithmic) spiral forms in nature as an opening to the study of all kinds of patterns the teacher could introduce. A good overview of the spiral and patterns in general can be found here: https://en.wikipedia.org/wiki/Logarithmic_spiral (note list of natural phenomena) and https://en.wikipedia.org/wiki/Patterns_in_nature
There of course are natural forms that replicate basic geometric forms like cones, lozenges, ovals, and spheres