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