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