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