Starfish first appeared in the fossil record in the Cambrian. The first known asterozoans were the Somasteroidea, which exhibit characteristics of both groups. Starfish are infrequently found as fossils, possibly because their hard skeletal components separate as the animal decays. Despite this, there are a few places where accumulations of complete skeletal structures occur, fossilized in place in Lagerstätten — so-called "starfish beds". By the late Paleozoic, the crinoids and blastoids were the predominant echinoderms, and some limestones from this period are made almost entirely from fragments from these groups. In the two major extinction events that occurred during the late
Spiny mouse 2017 in eLife, a team from the University of Kentucky described the role of macrophages in epimorphic regeneration. The subtype of macrophages found in African spiny mice produces a different immune response than the subtype that elicit scarring. Spiny mouse The term spiny mouse refers to any species of rodent within the genus Acomys. Similar in appearance to mice of the genus "Mus", spiny mice are small mammals with bare, scaled tails. However, their coats are endowed with unusually stiff guard hairs similar to the spines of a hedgehog; this trait is the source of the common name, "spiny mouse".