Temporal range: Middle-Late Ordovician
|An artist's illustration of Astraspis desiderata|
| †Astraspis desiderata|
This placoderm was preyed on by many creatures so it developed tough head and body armour to defend itself from other predators like sharks, other arthrodire placoderms and the massive, fearsome and deadly Dunkleosteus. Dunkleosteus would have been one of the few predators that could get through and puncture its tough protective bony armour covering its head and part of its body. It grew up to anywhere between 10 and 25 centimetres long and weighed around 500-700 grams to almost a kilo because of its tough protective and heavy body armour casing. It would have swam fairly slowly because of its heavy body armour so this would have been a major disadvantage when it came to predators.