Not all part in the Philippines that have this kind of food. Some Filipino doesn't know if these foods can be eaten. For me near in the shore and the sea near to us experiences a very low tide. The sea is very dry that you could see the stones under the sea. Not the normal stone, but the kind of stone that have life and can grow bigger and wider like this.
In short, this kind of stone's are part of living things in the sea. Like algae, seaweeds and shell that stick in the stone grow of it. As you can see the sea is experiencing is very low tide that you can walk into it far from the shore.
Low tide or hight tide you can find sea urchins in the sea. The difference of low tide is that you can easily find them and you can eat here. But what is sea urchins by the way? I'm not sure if there are different countries who have this kind of living things. I could say living things because they have lives. They can move if they wanted to. So, sea urchins can be found under the sea. Lot of sea urchins in the sea, they have different types and characteristics. One of the sea urchins that lives under the sand is what we called "dapaw-dapaw."(bisayan dialect) The most popular of them is "suwaki"(bisayan diake) which ia very delicious of them all.
This is suwaki
the most delicious of them all. This kind of sea urchins is the most popular and the most in demand. In demand because many people will buy for this just to eat this kind of sea urchins.
How to eat this kind of sea urchins?
You will cut this into half with sharp materials like knife. You should cut it well into half or else it's flesh will be wasted. Unfortunately this image I showed is emptied already. Where you can find the flesh but before the flesh there's an intestine like they said. You should be careful on eating this one, don't let your lipse touch the shell because it's very itchy and painful.Get the flesh of it by using a spoon.
Let's go to "dapaw-dapaw"
This kind of sea urchins that I was talking about who lives under the sand. This is not so delicious like "suwaki" but it's good to eat and also it's easy to find. There's a sign in the sand like it's a house of it. That's the place where we get with our bare hands or knife. They live not deep in the sand, maybe 2 or 3 inches from the sand above level.
How to eat this?
Just like eating"suwaki by cutting it into half. But you don't need to worry on eating this kind because it's not itchy. It's okay if you'll going to sip it. As you can see the white inside, that's it's flesh that you'll going to eat. It's flesh have lot of different colours, there are orange white and black. The orange is the delicious of them all.
The last but not the least "bangas"
Bangas(bisayan dialect) is the easiest sea urchins to find but I can't say it's not delicious or it's delicious. The taste of this just fine, the flesh of this one is not that hard but like a gum. 
Hehe, see what's inside of this kind of sea urchins. But this is not poisonous, we used to eat this before. The thorn of this one is hard, it's fine to touch it but don't pressed it. In eating of this is just the same from the other but you need a lot of effort in getting it's flesh. It's hard to remove and it's intestine.
There you have it, if you're worried what to pair with your rice food. Check the sea, maybe it's low tide and you can find many sea urchins to eat. Just a reminder, do not touch if you don't recognise them. There are other sea urchins are so painful because some of them have long thorns. Sorry I don't have image of them all.
If you want to know or to ask, just comment down and I'll answer it for you.
d' dreamboy,
@mrnightmare89