I've never seen one like this before.
It's chubbier than a cockroach, but flatter than a christmas beetle.
As you can see, the markings are very bright and symmetrical and they continue under the body.
May I respectfully suggest jjjnetticus chchchocminticus but in reality it's Eupoecila australasiaeotherwise known as the Fiddle beetle present in most of Australia including Tasmania but not WA.