What are Ordovican trace fossils, and what do they look like?
Trace fossils are marks or things left behind by living things do their thing,  they are indirect remains of organisms, coprolites (poop), footprints, egg shells, ect. If we found a fossilized beehive or beaver dam those would also be trace fossils. Bioturbation is a specific type of traces fossil, marks of disturbances of the sediment itself animals leave behind, trackways and burrows are the classics.
Identifying bioturbation is tricky in a lot of cases, there are thousands of kinds which makes it worse, there is no way to give a direct answer. Your best bet is to find out what particular bioturbation they are referring to.  Burrows, trackways, feeding trails, nest, hold marks the list is endless. there are nearly as many trace fossils as there are organisms that crawl or dig.  Worse they are often very contextual and need examination of  micro-structure.  What is obvious a trace fossil in one formation will look identical to the naked untrained eye to something that is obviously not a trace fossil in a different formation. Generally you want to a specialized experts opinion before if saying something might be bioturbation someplace you don't expect it.
Even from a single location you can have a wide variety of forms,  here are a few examples from the ordovician, ...the second of six periods of the Paleozoic Era, 485.4–443.8 million years ago.
Bioturbation


The photos from mars are not likely to be bioturbation but are almost certainly differential erosion of normal chemical variation in rock. They do not have any of the characteristics that scream &quot;this has to be biological activity&quot; like cross cutting bedding planes or parallel patterns. Sedimentary rocks are rarely homogenous and chemical processes combine with erosional ones can produce some weird results. for comparison here are a few things that are definitely NOT fossils.
**Pseudofossils AKA Leaverite **


Pseudofossils are things lake look like fossils to the untrained eye but are just rocks, usually the leftovers of a chemical or erosional process. the term leaverite comes from geologists telling others &quot;just leave're there&quot;