Spine
Nose
Feet
Mouth
Echinoderms
Purpuratus
Animalia
Strongylocentrotus
Toothpick
Dome
Porcupine
Pentamerous
Intertidal area only
Subtidal area only
On the beach
Both intertidal area and subtidal areas
Because sea urchins have large numbers of relatively big eggs
Because a sea urchin's egg is relatively big
Because the eggs make great omlettes
Because sea urchins have large numbers of eggs
Other sea urchins
Small fish
Sea cucumbers
Algae