Fossil Fools (Japanese: こだいポケモンパーク！アルフのいせき！！Ancient Pokémon Park! Ruins of Alph!!) is the 163rd episode of the Pokémon anime. It was first broadcast in Japan on September 7, 2000 and in the United States on September 15, 2001.
Ash, Misty and Brock have reached the famous Ruins of Alph. Summoned there by a note from Professor Oak they join him and an old student of his, Foster in a facility for studying Pokémon fossils. Foster has made an amazing discovery, live prehistoric Water-type Pokémon thought to be extinct for thousands of years! Does their appearance have anything to do with the interrupted water flow from a nearby reservoir? Watch as our heroes find out what's fishy with the freshwater!
Next, they are all seen walking along the road while Oak tells them he found out about a mysterious discovery. Then they meet up with Foster, a scientist and one of Professor's top students. Then he takes Oak aside and tells him that this is a very important matter and it would be dangerous if any information would be leaked, to which he replies by saying that Ash, Misty and Brock are serious Pokémon Trainers and won't tell anyone unless it is made public by Foster, to which the gang confirms the same thing. Foster agrees, then Ash notices a man washing a bone. Foster tells him that he's removing the dirt from a Fossil they just found by using a special device which uses a water jet in order to not damage the fragment.
After determining the fragment's source, the device stops working, with Foster telling they've been having had water flow problems lately. Oak asks about the water's source and Foster answers, telling it's a natural crystal clear water reservoir which is deep in the woods. The scene then turns to Team Rocket pumping the water into bottles and labeling them. Then they all daydream about what they will each do after getting rich from selling water. The pumper then stops working and the scene turns back to Oak admiring Foster's artifacts. Foster informs them that their studies have found that the first Pokémon appeared 2,000,000 years ago and all the Pokémon has its origins in the ancient seas. Misty is thrilled to hear the latter, again revealing her love for Water-type Pokémon. Then, ironically Brock drags Misty away from Foster by her ear.
In the following scene, Foster leads the gang to a forbidden entry saying it is a place 2,000,000 years in the Pokémon past. As the door opens, a robotic Aerodactyl is flying around. Foster names the place The Ancient Pokémon Study Park. It's a special interactive and unique environment which recreates the Pokémon world being set to be opened for the public next week.
They proceed to a lake where a huge statue of a Kabutops is seen preying on a fish. Then, Ash asks him about his mysterious discovery which Oak told them about. Foster tells them to wait when an Omastar and two Omanyte come out of the water. Initially, they all think the Pokémon are robots but Foster informs them that they're real. When the gang reacts to this, the Pokémon frighten up and dig in the sand.
After witnessing this, Oak reveals that it was an Omanyte who inspired him to become a professor. It all goes back when he was 6 years old and along with his class they visited a Pokémon museum where he saw an Omanyte shell. Foster then reveals how he discovered them. He believes that their natural habitat was disturbed so they came to this Park.
The scene turns to James trying to fix the pump while Jessie and Meowth are drinking water from the bottles. While repairing the pump, he discovers an Omanyte who was jamming the pump. Then, they proceed to make plans with the Omanyte willing to search for more of them, while the scene turns back to the main characters. There, they are seen watching the two Omanyte and the Omastar on the surveillance cameras. One more Omanyte and Omastar appear, and Foster reveals that the previous ones appeared the same day they had water problems.
The door opens, and another scientist enters informing them the water has stopped flowing completely. They all agree to go to the reservoir. Outside the building Ash, sends his Noctowl to scout the reservoir. The scene turns to Team Rocket where they are shown using the pump to take the Omastar and Omanyte out of the water. The scene reverts to the others who are shown to be in a SUV heading to the reservoir. Noctowl returns and Ash realizes there is something at the reservoir.
Meanwhile, Team Rocket loads their air-balloon with the Pokémon, when the others arrive. Then they start to recite the motto. Meowth explains them how they found the Pokémon, when Oak realizes the Omanyte and Omastar from the Park came when Team Rocket started pumping the water. After Foster tells them to return the Pokémon, Jessie declines sending her Arbok and James his Weezing. Arbok proceeds to use Poison Sting and Weezing Sludge but Pikachu dodges both attacks then uses Thunderbolt followed by a Tackle which sends them into Team Rocket and blowing up the pump. Jessie and James call their Pokémon back and proceed to lift-off with the Omanyte and Omastar.
Suddenly, the balloon stops due to the overload of Pokémon. Ash sends his Noctowl again and orders him to make a hole in the balloon bringing Team Rocket down to earth. Pikachu shocks them and the Omanyte and Omastar send them blasting off with Water Gun. The scene then turns to the Omastar and Omanyte as they are returning back in the water. Then a scene is shown where the Pokémon dig a hole in the depths of the water, which leads them to a waterfall connected to a cave full of Omanyte and Omastar.
The scene then cuts to Foster and Professor Oak saying goodbye to Ash, Misty and Brock.
One of the clay artifacts that is displayed in this episode also appeared in Me, Myself and Time, over three-and-a-half years later; and again in Bucking the Treasure Trend!, over nine-and-a-half years after its original appearance in this episode.
In the dub, when Ash tells Pikachu to use Thunderbolt (and when Misty points out that the Omanyte and Omastar would get shocked as well as Team Rocket), he says, "Pikachu, use Thunderbolt, Pikachu!" which is redundant as he says "Pikachu" twice in the same sentence.