Benthic organism i think!!
A geologist studies all of those.
No, they don't have organs and organ system.
Cells form tissues, Tissues form organs, Organs forms organ system; Unicellular have their own one cell only. So, it can't possible that they have organs or organ system.
Explanation is in the file
tinyurl.com/wtjfavyw
Answer:
The answer is natural selection
Explanation:
The modern theory of evolution was developed by Charles Darwin, an amateur English naturalist, in the 19th century
