Mouth
Nose
Spine
Feet
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
Both intertidal area and subtidal areas
Intertidal area only
Subtidal area only
On the beach
Pentamerous
Toothpick
Dome
Porcupine
Small fish
Algae
Sea cucumbers
Other sea urchins
Purpuratus
Animalia
Strongylocentrotus
Echinoderms