The Terrenumcarids 

Silverswimmers (Clade-Neotneycarids) continue to diversify as the ice age counties with large forums like the Doomcarid descendant from the Giant Riverin Silverswimmer being among the largest members of Pancrustacea and of the Arthropod phylum in general. 

However, one group is taking a completely different direction doing what many crustaceans have done before and moving on to try land. 

On the shore of the salt marsh of the Coastal Lowlands where the sea meets the land, two different but similar Silverswimmers meet on their morning forges. 

Both are members of the clade Terrenumcaridea-(Terrestrial-Shrimp) both evolved from the Soilswimmer of 225 MYH and by extension the Squibbion era Siltswimmer. 

The Ash-colored Arachlobster is the more terrestrial of the two only returning to the water to spawn and has completely lost all of its swimming legs having modified them into long walking legs to stride across the ground. 

A Lobster-sized animal the Arachlobster gets the other part of its name for its Arachnid looking appearance (even though they are neither Silverswimmers evolved from neotenic Caridea "True Shrimp") More confusing Arachlobsters hunt similarly to Coconut Crabs pouncing on their prey holding it with their first pair of limbs and killing it by snapping it's neck. Arachlobsters hunt small Tera Squids, Hoppers, Fish, and Blish they hunt through sent with pairs of long antennae that are highly reduced to nonexistent in other Silverswimmers. 

The other type of Terrenumcarid is very different the Tyrant Soil Sifter lives very much like the ancestral Soilswimmer dragging itself through the muck and gulping food into its downturned mouth. It is a very slow animal taking a considerable effort for its legs to pull itself across the mud leaving a trail in its wake. 

Although not much bigger in length it is considerably heavier than the Arachlobster as it doesn't need to move fast to hunt or escape predators it can simply sift through the sand and mud at its own leisure its hefty exoskeleton keeping it safe from attacks.

Unlike Arachlobsters that don't use water at all Sand Sifters will use water to transport themselves between feeding spots. Although they cannot swim the water is less stressful on their body letting them stride across the floor of the salt marsh. They will also use the water to molt finding a thick stand of Riceweed to shed their very thick exoskeleton in peace which can take several hours.