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