The life cycle of a sea urchin starts by spawning directly into the sea. First, the male spurts out his sperm. Then the female comes and spurts out her eggs. If the sperm and eggs touch, then a new baby sea urchin will form. After the male spurts out his sperm, more males and females come and spurt out their sperms and eggs. As a group thing there is a good chance that more baby sea urchins will form.

Sea urchins live in the mid-level or low-level of a tide pool. Sea urchins eat algae off of hard surfaces. Most of the time they eat seaweed. Sometimes they eat bits of plants and small animals. Sea urchins have hundreds of tiny, tubed feet. They have five teeth in the middle of their back side. Sea urchins use these teeth to pull, tear and rip off algae on the rocks.These teeth continue to grow throughout the sea urchin's life.

Diet:  seaweed, algae and bits of plants and animals
Size: up to 4 inches ( 10 cm)
Colour:purple and light pink
They have five teeth.
Relatives:  star fish and sea cucumber
Types:  Caribbean sea urchin, pencil urchin, Slate pencil urchin, purple sea urchin and sea potato.
Source:  Library Thinkquest