The mosaic sea star (Plectaster decanus) is a species of sea star found off the south coast of Australia. This five-armed starfish is distinguished by its bright colors. It gets is name from the color pattern that resembles a mosaic picture. A group of raised ridges covers its red upper surface and it is soft in texture. Its color ranges from orange to purple and red. This is one of the few poisonous sea stars. It can can cause numbness in humans if allowed to make sustained contact with the skin.