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