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