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