An observer of event in the surrounding for which I boil without warning till the mercury rise or fall to whom I will call you

I sleep in stone with silent might, a buried heart of darkest night. But wake me with the furnace flame, and I will bend yet stay the same. I help your blood, I build your blade - in earth and in the forge I'm made.

Just my first three: in a pod of green. My last three: a rodent’s stash, both descend from trees. My rounds are chambered in a shell of tweed. Crack the case, of Planters’ face. The solid, not the cream.

I wear a cap, but lack a head, I grow where light and warmth have fled. Though gills may line my underside, no fish are found where I reside.

I can be created in a glass, fun to play on, or hold ships. If I spiral out of control, I can be deadly or simply just spill out.