You find a piece of rock. it crumbles easily and has little bits and pieces of shells in it. is this an igneous, metamorphic, or sedimentary rock?

clinically, some people often have repeated allergies, eczema and respiratory infections or other parts of the infection, in this case, in addition to some routine tests such as tests for white blood cells, immunoglobulin series, lymphocyte subsets, etc., the five immune immunoglobulin tests are also necessary.