Which plant group is known for following features ?

a. Used as a packaging material for tans-shipment of living material.

b. They decompose rocks making the substrate suitable for growth of higher plants.

Species of Sphagnum, a moss, provide peat that have long been used as fuel, and as packing material for trans-shipment of living material because of their capacity to hold water. Mosses along with lichens are the first organisms to colonise rocks and hence, are of great ecological importance.