A long time passed and the girls still lingered. They discovered that most of the pools boasted anemones, some not unlike an ordinary land daisy with light-colored tentacles stretching ray-shaped from a yellow centre. When touched with an empty shell, the anemone would close over it, folding both the shell and itself into a tight brown ball, then open slowly and drop the shell. The only food the girls had with them was some sweet chocolate, so they experimented with this, watching the lovely living sea-flowers seize upon fragments held within reach of their feelers.
"I suppose it will give them frightful pains," remarked Frances at last, rising from her cramped position. "Goodness! the tide is coming!"
"Yes, but it's far out," replied Edith, casting a glance at the line of water, still distant a full half-mile. "Look, Frances, here's a tiny pink crab."
For a moment Frances again bent over the aquarium but soon started to her feet.
"Let's go back, Edith. We're a long way from shore and you know how very fast the tide comes in."
"Oh, is that crab gone? I thought you would mind where he went," said
Edith as she reluctantly rose. "I wanted to take him to Win."
The two began to retrace their way, at first over piles of red rock covered with seaweed, farther on over stretches of sand surrounding rock islands.
Just as they left the last of the solid rock a big wave came curling lazily along its side. For a second the water clung to it like fingers, then withdrew.
"Fran, we must run," said Edith quietly, but her face had grown pale.
Frances made no reply. Both ran as fast as they could across the stretch of level hard sand. Before they reached the first rock island, long fingers of foam again darted past at one side.