@ifunny inspired me, so if you don't like this and future posts like it, take it up with him. 😉

As a geologist, I keep some pretty neat rocks I've collected over the years on display in my house.

Today = Australian edition:
1) Honeycomb weathering of a carbonate-cemented sandstone; from the Victoria coast, unknown age
2) LAVA BOMB! (This one is actually SUPER cool, I'll add more about it in a reply); from Newer Volcanics Province, Victoria, 4 million years old
3) Ripples (like you'd see at the beach) recorded in the rock record via a sandstone; likely from South Australia, probably >500 million yrs old
4) Carbonate rock signed by Paul Hoffman, one of the first hypothesizers of Snowball Earth Theory; from South Australia, >1 billion years old (more on this in a reply too)
5) Same rock as above, different angle