Ammotrophus
Ammotrophus is a genus of echinoderms belonging to the family Clypeasteridae. The species of this genus are found in Australia. Species:

Ammotrophus arachnoides 
Ammotrophus crassus 
Ammotrophus cyclius 
Ammotrophus platyterus

References

Clypeasteridae
Echinoidea genera
Echinoderms of Oceania