Another Feather Rock Question

I bought some feather rock a while ago to use in my tank and I have just now decided to put some in the tank to see how it looks. I have read several threads saying you need to boil or bake it for the rock to get it to sink, well I just cleaned my rock off and scrubbed them with a wire brush and put them in the tank and they sank right away. My question is wether this is normal or should the rocks have floated from the start? I want to leave them in the tank for a while so I can decide if I like them or not and I am worried the are going to go crashing up any second. Has anyone had that happen where they put the feather rock in their tank and had them sink then suddenly come crashing up or do they stay down if the sink from the start? Once again I have not baked or boiled them yet. Thanks.