I always pick up spotty or speckled stones because they usually have interesting detail, revealed especially by close-up photos. This stone is a good example.
Stone of the Day #21 looks to me like an amygdaloidal stone. An “amygdale” (also known as an “amygdule”) is an infilled vesicle in an igneous stone – a vesicle is a tiny hole originally formed by a gas bubble in the cooled rock. These holes then fill with heated mineral-rich fluids which leave behind deposits of minerals such as quartz, chalcedony (agate), calcite and zeolites (zeolites are a group of minerals with a crystalline structure made up of silicon, aluminum, and oxygen). The term “amygdale” comes from the Latin for almond, reflecting the almond-shape of many such vesicles, although some amygdales can be very circular.
The main stone for December in the TumbleStone 2024 Calendar is a similar amygdaloidal one, also from Gemstone Beach. Another specimen can be found in this 2022 fossicking Post.
Go to Stone #1 in the Stone of the Day Series for November.
TumbleStone 
I like this one probably because of the black and green! Those speckled ones always catch my eye too!
LikeLike