Most are very textured, but some are quite smooth, depending upon the tree’s age, which can be hundreds of years, and environmental factors. A thin coating of bark that can peel off in strips covers the bells and prevents them from damage and would-be pests. Plant life thrives on some trees when seeds wedge into the bark and grow in the moist environment. I have seen plenty of cypress bells that have a gaping hole at ground level where fish and other swamp life hide.
What I enjoy is the sun’s warmth on the tree and the overall feeling of each tree’s energy. Those factors listed above influence the tree’s “heartbeat” to me. When sun shines on the bark, there is always the pleasant aroma of pine and in the third photo you can see the red sap leaking from a tree. Avoid that; it is super sticky, but don’t let it keep you from enjoying the tree like you would a friend.