In article ,
Jeff Layman wrote:

The things that I compost that do last for ever are (sea) shells, like
mussel, oyster, scallop or winkle. But I chuck them on my traditional
heap anyway. Avocado stones, peach/nectarine/plum stones, the harder
nut shells etc. take some years, but they can be left to do that in the
soil. I sieve them out for making potting compost, but not for spreading
on the garden.

Mango stones (? not sure what to call them) get hollowed out and the seed
coat remains. Does the same thing happen to avocados?

It's mango stones. That happens, but the coat then rots down fairly
fast (i.e. in a year or so). Avocados are very different, and the
oil has to leach out before they will rot - it takes a few years.

How do
peach/plum/nectarines ever germinate? The stones seem indestructible.
Maybe a mouse or squirrel thinks it's got a meal after gnawing in, only to
get a dose of cyanide to dissuade it.

Nope. They crack open from the inside.


Regards,
Nick Maclaren.