Shrewv
The shrewv split from its ancestor by returning to a more mobile lifestyle. This is a relative term; they creep along with pseudopods at their bases, taking hours to cross meters, but they do keep up constant slow travels.
Shrewvs, like other shevs, consist of large cells that secrete a hard shell. This is useful for maintaining internal pressure for such a large cell. The shells are made of blocks of minerals from the shrewv's environment, often including heavy metals that make them dangerous to eat, all smoothed over by deposits of aragonite that produce gentle waving contours.
Shrewvs continue to focus on consuming larger quantities of smaller food, filter-feeding abundant tiny organic particles and microbes. As a result, they have a much greater number of pseudopods that are much thinner. These reach outward to snag passing food and can retract into the shell when under attack, their thinner proportions making it now possible for them to retract entirely. As in the nucleus-sharing shev, these pseudopods also eventually get covered over in minerals and aragonite, developing into spikes. As a result of the changes, these spikes are more numerous and smaller too. These pseudopods give the shrewv a fuzzy appearance, with an underlying bristly layer from the thorns, so that from a large scale it looks as if the shrewv has fur growing over its shell.
The more active lifestyle comes with a slight development in senses. The shrewv now has simple photoreceptor spots to detect light. These develop out of repurposed pseudopods, ones that have not shrunken, as this allows them to peek outside the impregnable shell. They also retain the ability to detect dissolved chemicals around them and to feel with the pseudopods.
Shrewvs spend more time as independent cells than their ancestors, but they are still able to link up with additional cells to form larger groups. They connect using the pseudopods at the base, which they also use to transfer nuclei between conjoined cells. The multiple nuclei within an individual cell can then exchange genetic material. As a result, conjunction in shrewvs serves more as mating than as reef-building. Nonetheless, this act of mating may go on for months and involve many participants forming a temporary colony, which remains mobile throughout.
Reproduction occurs by budding a new cell off from a pseudopod. The smaller pseudopods mean that new cells are particularly tiny, with only a few nuclei to begin with, and they are very vulnerable while they're still growing their shells. For this reason, shrewvs are r-strategists; they bud off many young, only a few of whom will reach adulthood.