Another author, Moritz Kliver, described a small specimen of Arthropleura armata showing the underside, with a series of 7 pairs of limbs articulated with various other plates, including the sternites.

Following authors tended to view Arthropleura in connection to isopods, some believing it represented a very primitive Eumalacostracan crusteacean.

Waterlot also believed that Arthropleura was amphibious, living at the bottom of lakebeds, with occasional excursions onto the land where the humidity of coal swamps allowed it to continue breathing with its supposedly trilobite-like gills.

[7] The juvenile specimen described by Waterlot appeared to show various plant remains within the gut tract, more recently this has been seen as a taphonomic artifact.

Waterlot's cephalic limbs are now identified as paired ventral scleites, protecting the head like a car bumper.

[13] In 2021 a fossil, probably a shed exoskeleton (exuviae) of an Arthropleura (indeterminate species, as due to its exposure of only the underside of the carapace, ornamentation cannot be observed), was reported with an estimated width of 55 centimetres (22 in), length of 1.9 metres (6 ft 3 in) to 2.63 metres (8 ft 8 in) and body mass of 50 kg (110 lb).

[1] Arthropleura had large, flattened ventral sclerites and a pair of antennae with at least seven antennal articles at the front of its head.

The paired mandibles were small, composed of three segments, and fully internalized into the head, similar to centipedes rather than millipedes.

Unlike any living myriapods, they had stalked compound eyes, which despite also being known from the extinct stem-myriapod group Euthycarcinoidea, appears to be a derived trait evolved independently from the euthycarcinoids.

A crease ran down each side of the leg which probably allowed for stronger muscle attachment as an apodeme, and the ventral surface bore paired endites on each segment (actually macro-setae, set in sockets and presumably mobile).

[17][18] This has however also been questioned, with Rolfe and Ingham (1967) considering all of these plates to be simply sclerotized ventral integument responsible for reinforcing and buttressing the limb bases to enable locomotion for such a large animal.

[11] The rosette plate is divided into small triangular lobes - the creases between them probably functioned as internal apodemes, muscule attachment for the limbs.

The Montceau-les-Mines species (known from only juvenile specimens) has a band of 4 large tubercules on the paratergal lobe, which rise up into tall spines.

Many fossils of Arthropleura are found either before or after the dominance of such coal forests, and direct geological and paleobotanical evidence suggests its primary habitat was far more open.

In addition to large trackways, enormous burrows have been attributed to Arthropleura and arthropleurids generally, suggested to be made during periods of aestivation similar to hibernation.

[2] Additional evidence for this comes from the juvenile Montceau fossils, which demonstrate that the eyes were large and stalked, unlike any living myriapod.

The authors suggest that this could point to a semi-aquatic, amphibious lifestyle, capable of entering and exiting shallow bodies of water.

[1] It has been suggested that due to their large size, moulting (a stressful period even for smaller arthropods) probably occurred underwater, allowing its weight to be supported while its new exoskeleton hardened.

She suggested that during moulting, Arthropleura could have behaved like modern Scolopendra centipedes, moving in a worm-like fashion without use of their softened legs until they were hardened.

More likely, Arthropleura was capable of gigantism due to other generally favourable environmental and ecological conditions and lack of serious competition.