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