Rama wanted to cross the bridge to Lanka in order to save Sita from Ravana's clutches. He sat down to pray to the sea god. The sea god, Samudra, arose from the depths of the sea and told Rama to build a bridge across the sea.
All the monkeys got busy building the bridge by placing boulders. A tiny squirrel was watching everything from his burrow. He decided to help Rama. He began picking sand and scattered twigs and scurried back and forth from the shore to the sea. Little by little the squirrel had gathered an entire heap.
Rama noticed the dedication of this tiny creature. Picking it up on his palm, he warmly stroked the animal with his three fingers. Since then, it is believed that squirrels have three lines on their body.