This is a great example of a galaxy stone. These are lumps of basalt with bubbles of other minerals in them. The bubbles form in the rock as it cools from molten, leaving time to fill them with other things.

This is from Ayrshire, where the agates are pink, carnelian, and grey. This vesicular basalt from Scotland has white to pink hued vugs of minerals in the bubbles. The bubbles are particularly bulbous. A lapidary artist may wish to work this natural stone though it is a bit small for intricate work.