All galaxies have a dense core of stars. Spiral galaxies, however, have arms that are often visible. There are two kinds of spiral galaxies: barred, where there appears to be a line running from arm to arm through the core, and <span>ordinary, where there is no bar. @Badbunnyhunny</span>
<span> It is a hydraulic </span>system<span> used by echinoderms, such as sea stars and sea urchins, for locomotion, food and waste transportation, and respiration. The </span>system<span> is composed of canals connecting numerous tube feet.</span>
