The common Pillbug (Armadillidiidae), is a type of woodlice that commonly feeds on decaying vegetation and is found under logs, garbage pails or any other place where moisture can be found. Moisture is essential to pill bugs due to their breathing organs, which are like gills. Pill bugs, although often thriving in damp areas, have often been known to live in dry beds. Pill bugs’ defensive posture is curling up into a ball.

Little Bug thinks it's an Armadillo!

I used to call them Roly-Polies when I was younger and once witnessed the very unerving live birth of what seemed to be dozens of little Rolies on my parent’s coffee table. They also go by the names armadillo bug, potato bug, sow bug and a few other equally creative names.

Why are the weird to me?  They aren’t insects or even arachnids but are one of the few terrestrial (land) crustaceans. Yes they are actually little distant relatives of crabs and lobsters.  Anyways, lets get to the crazy-ass not-so-distant relatives:

1. Giant Isopod (of doom?)

A giant isopod may be one of approximately nine species of large isopods (crustaceans related to the shrimp and crabs) in the genus Bathynomus. They are thought to be abundant in cold, deep waters of the Atlantic. Bathynomus giganteus, the species upon which the generitype is based, is the largest known isopod and is the one most often referred to by the common name “giant isopod”.

Holy Shit! Big Roly-Poly!

French zoologist Alphonse Milne-Edwards was the first^[1] to describe the genus in 1879^[2] after fishing a juvenile male B. giganteus from the Gulf of Mexico; this was an exciting discovery for both scientists and the public, as at the time the idea of a lifeless or “azoic” deep ocean had only recently been refuted by the work of Sir Charles Wyville Thomson and others. Females were not recovered until 1891.

Giant isopods are of little interest to most commercial fisheries owing to the typical paucity of catches and because ensnared isopods are usually scavenged beyond marketability before they are recovered. However, in Northern Taiwan and other areas, they are not uncommon at seaside restaurants, served boiled and bisected with a clean lateral slice. The white meat, similar to crab or lobster in texture, is then easily removed. The few specimens caught in the Americas with baited traps are sometimes seen in public aquaria.

Maturing to a length between 19 and 37 cm (7.5 to 14.5 in)^[1], and maximally reaching a weight of approximately 1.7 kg (3 lb) in B. giganteus,^{[citation needed]} giant isopods are a good example of deep-sea gigantism (cf. giant squid); most other isopods range in size from 1–5 cm. Their morphology is nonetheless familiar to most people as giant isopods closely resemble their terrestrial cousin, the woodlouse: their bodies are dorso-ventrally compressed, protected by a rigid, calcareous exoskeleton composed of imbricate segments. The first of these segments is fused to the head; the most posterior segments are often fused as well, forming a “caudal shield” over the shortened abdomen (pleon) ^[1]. The large eyes are compound with nearly 4,000 facets, sessile and spaced far apart on the head ^[3]. There are two pairs of antennae.

The uniramous thoracic legs or pereiopods are arranged in seven pairs, the first of which are modified into maxillipeds to manipulate and bring food to the four sets of jaws. The abdomen has five segments called pleonites each with a pair of biramous pleopods; these are modified into natatory legs and rami, flat respiratory structures acting as gills. The isopods are a pale lilac in colour.

2. Cymothoa exigua - The Creepiest Crusty Ever

Cymothoa exigua is a parasitic crustacean of the family Cymothoidae. It tends to be 3 to 4 cm long. This parasite attaches itself at the base of the spotted rose snapper’s (Lutjanus guttatus) tongue, entering the fish’s mouth through its gills. It then proceeds to extract blood through the claws on its front three pairs of legs. As the parasite grows, less and less blood reaches the tongue, and eventually the organ atrophies from lack of blood.

Why God? Why?

The parasite then replaces the fish’s tongue by attaching its own body to the muscles of the tongue stub. The fish is able to use the parasite just like a normal tongue. It appears that the parasite does not cause any other damage to the host fish.^[1] Once C. exigua replaces the tongue, some feed on the host’s blood and many others feed on fish mucus. They do not eat scraps of the fish’s food.^[2] This is the only known case of a parasite functionally replacing a host organ.

And those are The Pillbug’s Crazy Cousins of the Deep!
As always, some text taken from wikipedia.