user67909: I can't figure why this block has 0 coinbase with 0 transactions... however still a valid block? Or it it empty? According to whalepanda this coinbase was sacrificed by unknown miner.
See the block at height
    501,726

user1850: Block contains "RSKBLOCK:Ý¿QzßýKÊwQP[9É:
ÔyüN9ÝW³GÆ$", so I think that it is related to www.rsk.co. Probably Sidechains synchronization.
EDIT:
Binary hex: "52534b424c4f434b3addbf517adf8ffd4bca7751505b39c9013a0d1fd479fc4e901b39dd57b347c624"
Source: https://blockchain.info/tx/9bf8853b3a823bbfa1e54017ae11a9e1f4d08a854dcce9f24e08114f2c921182?show_adv=true

user38618: It has no transactions other than the coinbase transaction. However, the transaction's coinbase output is 0 BTC. Here's the valuable piece of information that you are looking for:

Coinbase outputs may be set lower than the max. value (12.5 currently), and the block will be valid (if the difficulty is lower than the target, as always)

Also look at: https://btc.com/0000000000004c78956f8643262f3622acf22486b120421f893c0553702ba7b5
BTW, the miner loses money, for the price of being "cool".

67909: <p>I can't figure why this block has 0 coinbase with 0 transactions... however still a valid block? Or it it empty? According to whalepanda this coinbase was sacrificed by unknown miner.</p>

<p>See the block at <a href="https://btc.com/0000000000000000004b27f9ee7ba33d6f048f684aaeb0eea4befd80f1701126" rel="noreferrer">height
    501,726</a></p>
 1850: <p>Block contains "RSKBLOCK:Ý¿QzßýKÊwQP[9É:
ÔyüN9ÝW³GÆ$", so I think that it is related to www.rsk.co. Probably Sidechains synchronization.</p>

<p>EDIT:
Binary hex: "52534b424c4f434b3addbf517adf8ffd4bca7751505b39c9013a0d1fd479fc4e901b39dd57b347c624"<br>
Source: <a href="https://blockchain.info/tx/9bf8853b3a823bbfa1e54017ae11a9e1f4d08a854dcce9f24e08114f2c921182?show_adv=true" rel="nofollow noreferrer">https://blockchain.info/tx/9bf8853b3a823bbfa1e54017ae11a9e1f4d08a854dcce9f24e08114f2c921182?show_adv=true</a></p>
 38618: <p>It has no transactions other than the coinbase transaction. However, the transaction's coinbase output is 0 BTC. Here's the valuable piece of information that you are looking for:</p>

<blockquote>
  <p>Coinbase outputs <strong>may</strong> be set lower than the max. value (12.5 currently), and the block will be valid (if the difficulty is lower than the target, as always)</p>
</blockquote>

<p>Also look at: <a href="https://btc.com/0000000000004c78956f8643262f3622acf22486b120421f893c0553702ba7b5" rel="nofollow noreferrer">https://btc.com/0000000000004c78956f8643262f3622acf22486b120421f893c0553702ba7b5</a></p>

<p>BTW, the miner loses money, for the price of being "cool".</p>
