All blank have moveable spines that they use for protection. sea urchins
sea cucumbers
sea stars
brittle stars

Its a sea urchin

Explanation:

I took the test and that was the answer

ecological efficiency: % of usable energy transferred as

biomass from one trophic level to the next typical is 10% efficient (90% of

energy is lost),is diagramed as the pyramid of energy flow. then osprey eagle

are tertiary consumer and the shrimp are primary consumer, so to balance

mass of shrimp (1/0.1) / 0.1 = 100 kg 

some inherited genetic mutations can be good for the offspring, so the answer is different genetic mutations cause many forms of cancer.