Animal cells do not have any thick, durable cell walls (like the cells of plants or of fungi). Their thin membranes would be easily ripped by such silicon spike

Animal cells do not have any thick, durable cell walls (like the cells of plants or of fungi). Their thin membranes would be easily ripped by such silicon spikes. The durable materials, if any, can be only extracellular, like in bone tissues or cartilage tissues, where they fill spaces between and around the cells. As another poster has said, the durable, protective part of the skin is made by dead cells, which are shed and renewed. Being already dead, they would not be affected by scratches. On the other hand, eating some particles covered with such a surface with silicon spikes might be a bad idea, though the damaged cells from intestinal walls should also be eventually replaced, like those of the external skin.