Purple Tentacle drunk some waste causing it to be mutated and grow arms. Dr. Fred attempted to send Bernard, Hoagie and Laverne to the yesterday and turn it off, before Purple drunk from it. According to the future Purple Tentacle, it was it who designed the Sludge-O-Matic™ in the future and sent the plans to the past so that Dr. Fred would construct it and cause the Purple to be mutated in the present.