So the first one would be Petrified Treeguards.
Nothing super big, these Treeguards would have the same spawn requirement as normal Treeguards.
They could be spawned from normal chopped evergreens OR petrified ones getting mined/destroyed.
I think it would be cool if they had less hp due to being more fragile but dealing more damage with their sharp hands. As well as having a chance to drop nitre/rock/flint when damaged/hit, and seeing it slowly crumble.
Drops: Living logs( less than normal treeguards), Rock/Flint/Nitre (Larger amount than normal petrified trees), Bone Shards?(maybe?)
Second would be Rock Lobster droppings! (yep)
I think if occasionally rock lobsters pooped out a mineral that looked like stone fruit that you could pick up and mine for a completely random mineral. rock/flint/gold/gems/marble, it would make them cool for more farms!