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