Question 5 5. The outer covering of a diatom is called a Time Elapsed: 26 Minutes, 39 seco known as the while the lower "lid" is called the . Inside, the diatom contains chloroplasts with the photosynthetic pigment Round diatoms are classified as Long diatoms are classified as pennate. Pennate diatoms may or may not have a seam called a 4. The of a ciliate gives the protist strength and flexibility. Food is internalized through a mouth located at the Water regulation is controlled by the The exchange of genetic information is achieved by "swapping" between two ciliates. .