This is a very rare Lower Cambrian trilobite. It is a complete Mesonacis eagerensis from British Columbia, Canada. This type is very unusual - it has five spines that come off the tail section of the trilobite. Although this specimen does not have all of these spines preserved, it is a fabulous example. You can easily see by the non-bulbous glabella, long, thin thorax, and truncated pleurons that it is not your common Olenellus. In fact, it has many of the same characteristics of the classic trilobite, Mesonacis vermontanus. This specimen also has its counterpart included, which makes this piece even more valuable. This is a very detailed example of this extremely collectible Lower Cambrian trilobite.