They were communal chameleons, often working together for defensive and offensive reasons. Their bodies were flattened spheroids from which long, thick tendrils extended, resembling jellyfish, but with more substance. Their flesh had an elastic quality and they were very strong. Generally, they were small enough to be picked up relatively easily by humanoids.
In 2376, Taran'atar devised a holoprogram challenge in which Colonel Kira Nerys had to capture a Rintannan. Unfortunately, she failed the challenge by taking shelter in a structure which turned out to be many Rintanna and was captured herself. (DS9 - Mission Gamma novel: Twilight)