BICON is the official database for import conditions. You should be able to search it to get exactly what you need.
For example, a search for egg shell ornaments gave me the following result:
a. A Department of Agriculture and Water Resources import permit is not required.
b. Conditions of Administration
Documents must be provided with each consignment which:
1.1. identify the consignment e.g. entry number
1.2. identify all goods being imported as part of this consignment e.g. invoice or waybill or importer’s manifest
1.3. describe the goods being imported (where not clear). Example 1: Product XRab = Purified protein derived from rabbits. Example 2: Product AX = Synthetic antibiotic. Example 3: Comte = Cheese.
For further information please contact:
Regional - Clearance assistance
Canberra - Administrative assistance or technical assistance: email or phone 1800 900 090
c. Professionally prepared undecorated and decorated blown eggs or egg shell ornaments/paintings may be imported without treatment provided the product is free from organic materials. Egg shell ornaments may be painted or lacquered.
d. All egg ornaments and paintings are subject to inspection on arrival. Blown eggs that appear not to have been professionally prepared, or where the cleaning process is unknown, may not be imported unless treated by one of the following methods:
Washing the outside and inside of the shell with 2% sodium hypochlorite for a minimum of 10 minutes, or
1% Virkon or 1% Virucidal X, or
Gamma irradiation at 50 kGray.
Consignments that do not meet the above conditions must be exported or disposed of.