Generally, an external fixator is mounted quite securely to the bone, and can withstand mild contact, any positioning of the body, and oftentimes even weightbearing immediately after surgery. In fact, it is often more comfortable to pick up the leg by grabbing the fixator, rather than holding the leg itself.he fixator is composed or one or more metal bars and rings, which in turn connect to a child via metal pins and wires. By gradually manipulating the fixator on the outside, we can carefully control the position of the bones and joints on the inside.
Habitat and Distribution. Pin this Image. Green sea urchins used to live in cold waters of the sub Polar Regions. They live in Northern cooler part of the Pacific and Atlantic Ocean. Some also live in the Arctic too. The sea animal can be found in rocky sea beds. They often live in the low depth tidal zones.
Sea urchins and sand dollars (Echinoidea) are a group of echinoderms that are spiny, globe or disk shaped animals. Sea urchins and sand dollars are found in all the world's oceans. Like most other echinoderms, they are pentaradially symmetrical (the have five sides arranged around a central point). Sea urchins range in size from as small as a couple of inches in diameter to over a foot in diameter. 1  They have a mouth located on their upper part of their body (also known as the oral surface) although some sea urchins have a mouth located towards one end (if their body shape is irregular).