This is a showcase of many different species of Martian trilobite.  I have omitted the terrestrial closest matches from this gallery, but you can see them by clicking the "more information" links.  I have 16 different specimens in this gallery but many, many more exist.

source	organism type	enhanced image	marked image
The original NASA/JPL image link is here Located on Bounce Rock	trilobite more information
The original NASA/JPL image link is here Located in Charlie Flats	trilobite more information
The original NASA/JPL image data is here	trilobite more information
The original NASA/JPL image link is here	trilobite more information
The original NASA/JPL image link is here	trilobite, rolled more information
The original NASA/JPL image link is here	trilobite, rolled more information
The original NASA/JPL image link is here	two trilobites, rolled more information more information
The original NASA/JPL image link is here	rolled trilobite, identical to those above more information
The original NASA/JPL image link is here	rolled trilobite, identical to those above more information
The original NASA/JPL image is here	rolled trilobite from Sol 049,  identical to Elrathia on Earth (far right) more information
The original NASA/JPL image is here	rolled trilobite from Sol 049 more information		very similar to specimen above
The original NASA/JPL image link is here	roller trilobite from Sol 555 more information		identical the the specimen above from Sol 049
The original NASA/JPL image link is here	rolled trilobite from Sol 014  (compare to terrestrial trilobite at far right) more information
The original NASA/JPL image is here	trilobite from Sol 593 more information
The original NASA/JPL image link is here	rolled trilobite from Sol 558 more information compare to trilobites below- identical

    There are dozens more (too many to easily classify and present) of these organisms in the various Opportunity images.  Their shapes and forms are almost identical to many of the terrestrial trilobites.  These are in no way related to the terrestrial trilobites, but they show the same sorts of forms and diversity that trilobites on Earth show in the fossil record.

This image is a collection of rolled trilobites from the terrestrial fossil record, and many of them are indistinguishable from the Martian specimens in the above images.    These are not as eroded and show their features more clearly than most Martian fossil trilobites.    Image used without permission; originally from paleozoic.org