premise: eating something has a negative impact on that something sent2: a spine is a part of a cactus that is hard and located on the outside of the cactus sent3: animals eat cacti sent4: something hard / something strong can be used for protection sent5: if something has a negative impact on an organism then that organism must protect itself from that something sent6: protecting a living thing has a positive impact on that living thing 's survival.
hypothesis: pencil and paper underwent a physical change