Moonstones are beautiful rocks with their main use for cichlid aquaria. They are very densely packed with calcium. So keep in mind that your KH and pH will go up when waterchanges are not done regularly.
Lava rock is popular in planted aquariums due to it's rough texture its ideal for planting mosses on. It can also be used stacked upon one another to build the hardscape of your aquascape. Also creating caves for Shrimp and fish to hide in.