The Sea Apple is also known as the Violet Sea
Urchin, but unlike classical sea urchins, it has neither spines
nor teeth. It basically feels like a sack of purple velvet with
lines of bright yellow mini-tentacles running down its sides. The
yellow tentacles are tipped with suction pads, allowing the Sea
Apple to climb. Here are a series of pictures of it as it
"woke up" and climbed up the side of the glass.
Notice that the Sea Apple now has a
"waist". This is the way that it climbs up the glass,
undulating slowly as it goes.
Here it is, about 2 inches above the substrate.
This all took less than 2 hours.
Here it is, from the side.
Here you can see the Sea Apple's mouth,
surrounded by the crown of feeder tentacles. It slowly moves the
tip of one tentacle to its mouth, then moves the tentacle away,
and then moves the next tentacle to its mouth, in rotation. The
deliberateness of this simple creature is wonderful to behold.