Monster Blood

Monster Blood is a green substance that is similar to a mixture of Mars Mud and Silly Putty. In Monster Blood, it had a spell put on it that made it consume things. Also, anything that consumes it will grow huge like a giant.

The Books
Monster Blood first appeared in the book Monster Blood where it is found in an old toy store in a dusty metal can which is opened by Evan and Andy, soon afterwords Evan's dog Trigger eats some, growing very large. It only does this because there is a spell put on it by a young witch named Sarabeth. Again, it apeared in Monster Blood II, when "Cuddles" the class Hamster eats it. Evan must eat some to combat the evil beast. At the end, when the Monster Blood's expiration date kicks in, Andy gives Evan some more from Europe. It was in Monster Blood III and that time Evan accidentally ate some, and grew over fifty feet tall. Finally, for the last book in the original Goosebumps series, Monster Blood IV, where it comes in a can, but is blue, and multiplies when exposed to water. The blood is also carniverous, evil, and has fangs. This blood is actually not a toy at all, but an aquatic military superweapon. The blue Monster Blood also makes a person multiply when someone eats it. Then in the third Goosebumps HorrorLand book, "Monster Blood for Breakfast!" ,the Monster Blood was a "12 hour Trial Strength" version, and it came in a plastic egg and made a new character, Matt Daniels, grow about twelve feet tall. It then followed him to HorrorLand where it sucked up Sheena Deep and a horror named Byron who saved Matt and Sheena's brother, Billy. It also appeared in the television episodes Monster Blood and More Monster Blood, where airline food makes it shrink. It will only stop growing when it is put back in its jar.

Trivia

 * In Monster Blood II, it is revealed that Monster Blood has an expiration date, causing the magic to wear off. This is the only known way to defeat the Monster Blood.
 * In Monster Blood II, it is revealed that Monster Blood is sold in Europe (Germany).
 * In the TV episode, the Monster Blood seems more sensitive to the touch and bouncy.
 * Monster Blood also appears in Escape from the Carnival of Horrors and Beware of the Purple Peanut Butter Give Yourself Goosebumps books. It is also mentioned as a puzzle in One Night in Payne House (the reader needs to know the color of Monster Blood, in order to solve something.)
 * The blood in Monster Blood IV is not the regular Monster Blood, but actually an aquatic military superweapon. This blood multiplies when it is exposed to water and more resembles slugs or snails than slime. The blood has eyestalks, and mouths with razor sharp teeth. However, like the original Monster Blood, if you eat it, you will change, as you become mean, can't stop drinking water, and multiply when you eat the blood in Monster Blood IV.
 * In Monster Blood for Breakfast!, the monster blood comes in a plastic egg like silly putty.