Colored pencil and graphite Nitzchia is another ice algae diatom. It forms chains, star shapes, and complex patterns, and its more flattened shape gives it more surface area to absorb light since there is less light in and under the ice than in open water. Leave a Reply Cancel Reply Your email address will not be published. Name* Email* Website Comment Notify me of follow-up comments by email. Notify me of new posts by email.