The echinoderm that differs from all others in that it lacks an endoskeleton, and only retains small bony pieces in its skin is the

(A) sand dollar

(B) sea lily

(C) brittle star

(D) sea cucumber

About __ of the mass of the cell is water

Identify two examples of chemical reactions that you have encountered during the last week. identify an exothermic and endothermic reaction. explain.

The many stone tools, fragmentary animal bones, and teeth found at gran dolina, spain, indicate that hominids there? a. processed and consumed animals and other hominids. b. did not differ appreciably from earlier asian homo erectus. c. were similar to later homo sapiens. d. none of the above