Prepare wet mount of diatoms 2. Observe the organisms and describe their form. Are they centric, pennate or both? The organisms are both centric and pennate. 3. Detect locomotion. What is the body form of motile diatoms? Centric diatoms 4. Observe a single centric form on high power and note the intricate geometric pattern of the cell wall. Can you detect the two halves? 5. Look for chloroplasts. 6. Observe diatomaceous earth and identify pennate and centric forms. Results: Figure 2: Diatoms Lab Study A: Brown algae Procedure: Observe examples of brown algae on demonstration.