I think it is the 4th one, Not 100% sure.
Answer:
Geodes
they are natural rocks with crystal formations naturally occuring inside.
you wont know what the crystals inside look like until you open it yourself, hence getting more people to buy due to its surprise factor.
Please let me type this I have horrible handwriting and I know you wouldn't be able to read it and typing is so much more neat and faster! please consider letting me.
Venn diagram. Hope this helps!<span>A Venn Diagram is a </span>graphic organizer<span> that is made up of two or three overlapping circles. In mathematics, Venn diagrams are used to visualize the relationship between two or three sets. Venn diagrams can also be used to compare and contrast the characteristics of any other items, like groups of people, individual people, books, characters, animals, etc. The </span>English mathematician John Venn<span> invented the Venn diagram in 1880. </span>
